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September 1952 E-846 

United States Department of Agriculture 
Bureau of Entomology and Plant Quarantine 
LIBRARY Agricultural Research Administration 

STATE PLANT BOARD 



A DIGEST OF INFORMATION ON ALLETHRIN 

By 
R. C. Roark 
Division of Insecticide Investigations 



irV. S. GOVERNMENT PRINTING OFFICE : 1952 O - 221857 



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CONTENTS 

Page 

Introduction L 

Nomenclature A 

Physical characteri sties 5 

Synthesis 

Synthesis of allethrin 6 

Synthesis of chrysanthemum monocarboxylic acid 7 

Synthesis of 2, 5-dimethyl-2, 4-hexadiene S 

Alternate synthesis of 2, $-dimethyl-2,^-hexadiene 8 

Analysis 

Production H 

Patents 12 

Specifications 12 

Allethrin in aerosols 13 

Stability of allethrin and its formulations 14 

Use of synergists with allethrin 

MGK-264 15 

n-Propyl isome 15 

Sulfoxide 16 

Piperonyl butoxide 16 

m-Nitrobenzamides 17 

Comparative value of synergists for allethrin 17 

Allethrin stereoisomers 20 

Analogs of allethrin 22 

Toxicology 23 

Classification of insects against which allethrin has been tested 26 

Orthoptera 

Blattidae 26 

Thysanoptera 

Thripidae 27 

Homoptera 

Aleyrodidae 27 

Aphidae 28 

Cicadellidae 29 

Coccidae 29 

Heteroptera 

Coreidae 29 

Lygaeidae 30 

Miridae 30 

Pentatomidae 30 

Anoplura 

Haematopinidae 30 

Pediculidae 30 



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Coleoptera 

Anobiidae 31 

Chrysomelidae 31 

Coccinellida 32 

Cucuj idae 32 

Curculionidae 32 

Derraestidae 32 

Scarabaeidae 33 

Tenebrionidae 33 

Lepidoptera 

Hyponomeutidae 33 

Papilionidae 33 

Phalaenidae 34 

Phycitidae 34 

Pieridae 35 

Pyraustidae 35 

Sphingidae 35 

Hymenoptera 

Formicidae 36 

Diptera 

Culicidae 36 

Drosophilidae 37 

Hippoboscidae 37 

Mycetophilidae 37 

Muscidae 38 

Tabanidae 40 

Acarina 

Argasidae 40 

Ixodidae 41 

Tetranychidae 41 

This digest has been prepared in response to numerous requests for 
information concerning the Bureau of Entomology and Plant Quarantined 
new synthetic insecticide, allethrin. This product, because of its high 
toxicity to insects and its non-toxicity to warm blooded animals, has 
excited great interest among entomologists, chemists, insecticide manu- 
facturers, food processors and public health officials. Information on 
the chemistry, economic status, toxicology and insecticidal value of 
allethrin has been collected and is presented in the form of a digest in 
which reference is made to many anonymous articles, press releases and 
advertisements in order to present in detail the early history of the 
development of allethrin by the Bureau. These references would normally 
not be included in a bibliography issuing from the Bureau of Entomology 
and Plant Quarantine. 



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INTRODUCTION 

The achievement of Schechter, LaEorge and Green in synthesizing 
allethrin was first made public by Bishopp (U7) in a statement dated 
March 11, 191+9. 

Al though considerable work had "been done by Swiss and British 
workers on the chemistry of the active principles of pyrethrtnn flowers, 
the final structures of pyrethrins I and II and cinerins I and II were 
determined mainly by LaEorge and associates in 19^7 as the result of 
15 years of research. Cinerin I was chosen as the object of synthesis 
because of its simpler structure and greater stability. Workers in 
England had already devised an improved synthesis of chrysanthemum mono- 
carboxylic acid, the acidic portion of the molecule. The problem there- 
fore was reduced to the preparation of cinerolone, the ketoalcoholic 
part of cinerin I. In 19^8 Schechter, LaEorge and Green finally were 
able to devise a general synthesis for cyclopentenolones of the type of 
cinerolone and a stereoisomer of cinerolone was prepared. V/hen esterified 
with chrysanthemum monocarboxylic acid it gave a product highly toxic to 
house flies. Other analogs were also prepared, but the ester which proved 
to be the best with regard to toxicity and knockdown effect on house flies 
and also from the standpoint of commercial production was the ester having 
an allyl side chain. 

The United States Department of Agriculture (l8j?) on March IS, I9H9, 
issued a press release announcing this new pyre thrum-like chemical and 
on May 1 of the same year it issued a picture story ( 186 ) which depicted 
LaEorge, Schechter, G-reen and Gersdorff performing operations having to 
do with the synthesis and biological testing of the new synthetic. The 
information in these departmental releases quickly appeared in the public 
press and in trade and technical journals (l-%) where the synthesis of 
allethrin was hailed as an achievement comparable with that of the syn- 
thesis of rubber. 

NOMENCLATURE 

The product now called allethrin was referred to as a "pyrethrin- 
like ester" and as a "homolog of cinerin I" in the original release by 
Bishopp. The release of March 18, I9U9 referred to "pyre thrum-like 
chemicals" and the picture story of May 1, 19*+9 mentioned "synthetic 
pyre thrum-like material" and the "new pyrethrum synthetics". Items in 
technical and trade journals referred to Schechter and LaEorge 's achieve- 
ment as the synthesis of an "isomer of cinerin I" and of a "homolog of 
cinerin I". In July I9H9 an editorial in a trade journal (Anon. 6) spoke 
of "synthesizing pyrethrum" and a news item in the same issue (Anon. J) 
was headlined "Penick synthesizes pyrethrum" although the article stated 
that the "allyl homolog of cinerin I" had been produced. Later articles 
referred to "synthetic pyrethrins", "so-called synthetic pyrethrum", and 
"synthetic pyrethrum". 



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This confusion in names was ended when the new name "allethrin" 
was coined by the Interdepartmental Committee on Pest Control (Rohwer 
150 ) to designate the insecticidal chemical dl-2-allyI-l4-hydroxy-3- 
methyl-2-cyclopenten-l-one esterified with a mixture of cis and trans 
dl-chrysanthemum raonocarboxylic acids. Although not officially announced 
until May 15, 1950, "allethrin" was revealed as the new name for the 
allyl horaolog of cinerin I on March 20, 1950 at a meeting at the Boyce 
Thompson Institute, Yonkers, New York, sponsored "by the Carbide and Carbon 
Chemicals Division of the Union Carbide and Carbon Corporation for the 
purpose of announcing the first commercial synthesis of allyl cinerin 
(Anon, il-li). 

Before the name allethrin was announced Starr et al. ( 172 ) sug- 
gested that the allyl homolog of cinerin I be called "devinylpyrethrin 
I H , or in abbreviated form "DTPy I". In England allethrin has been 
called "allylrethrin" (Blackith ^9) and Harper's (^6) nomenclature 
"synthetic dl-allylrethronyl dl-cis-trans-chrysanthemate" has been used 
by Galley (J^) and by Elliott et al. (66). 

Although Rohwer's announcement applied the name allethrin to the 
"substantially pure" chemical those in the insecticide industry have 
urged that it mean 100 percent material (Moore 131 ). 

Certain trade names have been applied by S. B. Penick and Company 
to allethrin, for example, Allexcel 20 ( 1U3 ) and Pyresyn (1$, lWQ . 

According to Erear (7*0 Allexcel 20 contains 1 percent of allethrin, 
5 percent of n-propyl isome, 10 percent of butoxyethanol, and Sh percent 
of oil. Allexcel 80 emulsifiable contains 3 percent of allethrin, 28. U 
percent of n-propyl isome, 20. 3 percent of methylated naphthalene, and 12.1 
percent of oil. Pyresyn technical contains 75 percent of allethrin and 
25 percent of related compounds. 

PHYSICAL CHARACTERISTICS 

Commercial allethrin has the following physical properties. — McNamee 
( 120 , 121), Moore (131). 

Appearance Clear, bromish 
Color on Gardner scale 15 

Specific gravity at 20/20 1,005-1.015 

Refractive index at 30* C. I.5OIO-I.5035 

Refractive index at 20° C. I.50H0 
Acidity calculated as 

chrysanthemum monocarboxylic 

acid 4. 3 percent 

Odor Mild, unobjectionable 

Treon insoluble ^0.1 percent 



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SYNTHESIS 

The synthesis of allethrin is accomplished in 13 steps, 6 steps in 
making allethrolone, 6 steps in making chrysanthemum monocarboxylic acid 
chloride, and a final step in combining these two components. 

The reactions involved are shown below. 



Synthesis of Allethrin 
CH3COCH2COOC2H5 (Ethyl acetoacetate) 

♦ CH 2 = CHChgCl (Allyl chloride) 
+ NaCX^H^ (Sodium ethylate) 

I 

CH-COCHCOOC^PL (alpha- Allyl acetoacetic ester) 
CH 2 CH = Cfi^ 

♦ Alkali 

1 
I 

CH2= CHCH 2 CH 2 C0CH3 (Allyl acetone) 
+ (C 2 H 5 0) 2 C0 (Ethyl carbonate) 
+ NaOCH^ (Sodium methylate) 



CH 2 = CHCH 2 CH 2 C0CH2COOC2H5 (gamma-Allyl acetoacetic ester) 
+ Alkali 

i 

CH 2 = CHCH 2 CH 2 C0CH 2 C00K (salt of gamma-Allyl acetoacetic acid) 

+ CH3COCHO (Pyruvaldehyde) 

J* 
CH3C0CH0HCH 2 C0CH2CH 2 CH = CH 2 (3-Hydroxy-8-nonene-2,5~dione) 

+ Alkali 

CHo 
1 * 

^C C — CH 2 CH = CH 2 

H(K| 

HgC C=0 (Allethrolone) 



- 7 - 

+ (CH 3 ) 2 C \ 

| ^CHCOCl (Chrysanthemum monocarboxylic acid chloride) 
(CH 3 ) 2 C = CH - CH^ 

CH3 
t 

C 




(CH 3 ) 2 C ^C N C - CH 2 CH = CH 2 



H \\ 



I J^CHCOO 
(CH 3 ) 2 C = CH - CH 

H 2 C C = 

Allethrin 

Synthesis of Chrysanthemum Monocarboxylic Acid 
C 2 H500CCH 2 NH 2 .HC1 (Glycine ethyl ester hydrochloride) 
+ Acid ♦ NaN02 (Sodium nitrite) 

1 

C 2 H 5 OOCCHN 2 (Diazoacetic acid ethyl ester) 

+ (CH 3 ) 2 C = CHCH = C(CH 3 ) 2 (2,5-Dimetbyl-2,4-hexadiene) 

♦ Copper catalyst 



(CH 3 ) 2 <r 

\ ^^-CHCOO^Hc (Chrysanthemum monocarboxylic acid ethyl ester) 
(CH 3 ) 2 C = CH-CH 

+ Alkali 

1 

(CH 3 ) 2 C^ 

I ^CHCOOH (Chrysanthemum monocarboxylic acid) 
(CH 3 ) 2 C = CH-CH*^ 

+ S0C1 2 (Thionyl chloride) 

I 

(CH 3 ) 2 C^^ 

^.CHCOCl (Chrysanthemum monocarboxylic acid chloride) 
(CH 3 ) 2 C = CH-CH' 



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Synthesis of 2 > $-Dlaethyl»2 > 4"Hexadiene 
CH ~ CH (Acetylene) 
+ CH3COCH3 (Acetone) 
+ KOH (Potassium hydroxide) 

! 
(CH 3 ) 2 C(OH)C ^C(OH)(CH 3 ) 2 (2,5-Dimethyl-3-hexyne-2,5-diol) 

♦ Catalyst + H 2 (Hydrogen) 

(CH3) 2 C(0H)CH2CH2C(0H)(CH 3 ) 2 (2,5-Dimethylhexane-2,5-diol) 
+ Catalyst 

(CH^C = CHCH = C(CH 3 ) 2 (2,5-Dimethyl-2,4-hexadiene) 

Alternative Synthesis of 2 > 5-Dimethyl-2 > 4.-Hexadlene 

CHg = C(CH 3 )CH 2 C1 (Methallyl chloride) 

♦ Mg (Magnesium) 

/ 
CH 2 = C(CH 3 )CH 2 CH 2 C(CH 3 ) = CRj (2,5-Dimethyl-l,5-hexadiene) 

♦ Catalyst 

v/ 

(CH 3 ) 2 C = CHCH = C(CH 3 ) 2 (2,5-Dimethyl-2,4-hexadiene) 



The details of the reactions are described in the following papers: 

21>21>5Z>22jto>Q>32j32> 1Q0, 2Q2l> 2£*> Ul> ±22> ±2k> 12i> ±&t 
157. 158. 160. 161. 



- 9 - 



Cupples (62, 65 ) determined the infrared spectra of natural cin- 
erolone and synthetic 2-(2-butenyl)-k- hydroxy-3-raethyl-2-cyclopenten-l- 
one over the wave length of 2 to 15 microns. The spectra indicate that 
the compounds are cis-trans isomers and that the naturally occurring 
compound is the cis form and the synthetic compound the trans form. The 
spectra confirm the molecular structures as determined "by Harper and "by 
LaForge and coworkers. 

In 1952 LaForge et al. ( 113 ) reported that esters of allethrolone 
are saponified to the combined acid and to 2-allyl-3-methyl-2,U-cyclo- 
pentadienone which undergoes the Diels-Alder reaction yielding a dimeric 
compound as the main product. The dimer exhibits the reactions character- 
istic of carbonyl bridge compounds. It furnishes "both a mono- and a 
disemicarbazone and upon heating sheds carbon monoxide with formation of 
a tetrasubstituted indanone. These reactions of allethrolone esters on 
saponification probably would occur with all esters of U-hydroxycyclopen- 
tenones including the pyrethrins. 

ANALYSIS 

Technical allethrin as produced commercially contains between 75 and 
95 percent of allethrin. Of the methods proposed for the assay of technical 
allethrin, the hydrogenolysis method and the ethylenediamine method are 
the two that are chiefly used at present. "Both are considered tentative 
methods by the Insecticide Chemical Analysis Committee of the Chemical 
Specialties Manufacturers Association. — Haring ( 93 f 9*0. 

The hydrogenolysis method is based on the method proposed "by LaForge 
and Acree (Soap and Sanit. Chem. 17(l): 95-98, 115) in 19U1 for the 
determination of the pyrethrins and depends on the cleavage of the ester 
by hydrogenation of the sample in isopropanol employing a palladium oxide- 
barium sulfate catalyst. The location of the cleavage is shown in the 
following structural formula: 




v 



-5r-CH X C - CK 2 - CH = CHg 



tt 



( CH3) 2 C=CH-CH-e( 0^3)2 S ^2 — C " ° 



In addition to hydrogenolysis of the ester group and saturation of 
the double bonds, it is probable that the cyclopropane ring of chrysan- 
themum monocarboxylic acid is opened. The acidity produced is titrated 



- 10 - 



after filtration of the solution. In one version of the method, the 
titration is carried out at the boiling point, whereas in a later version, 
the titration is performed at room temperature. In the latter case, an 
amount of alkali equivalent to the free acidity of the sample plus 1.00 ml. 
of 0.1 N alkali is added to the solution "before hydrogenation to activate 
the catalyst. Appropriate corrections are made for the free acidity originally 
present in the sample, for reagent blanks and for the catalyst activity. 

The ethyl en ediamine method proposed by the Carbide and Carbon Chemicals 
Company deoends on the following reaction of allethrin with ethylenediamine: 



HC-COO- 



r\ 



(CH 3 ) 2 C=CH-CH~C(CH 3 ) 2 



CH 
1 

C 



.CH 



3 



CH« 0=0 



C-C!2~CH=CH 2 



NH 2 CH 2 CH 2 NH 2< 



HC-C00H* KHpCHp CH P KH P 

/\ 
(CH3) 2 C=CH-CH-C(CH3) 2 + 



il 
CH 



^ 



^ 



f3 

C-CH 2 -CH=CH 2 



C=0 



/» 



Dim or -> Poly-iUA^ 

- Cyclic iminc 
Structuro 



After the addition of pyridine, the chrysanthemum monocarboxylic 
acid is titrated with 0.1 IT sodium methylate in pyridine. Suitable cor- 
rections are made for blanks on reagents, and for chrysanthemum monocar- 
boxylic acid, acid chloride, and acid anhydride originally present in the 
sample. The reaction with ethylenediamine is carried out for l/2 hour at 
98° C. or for two hours at room temperature (25°C + 2° C.). 

A color test for allethrin was described in 1952 by Feinstein (72). 
A solution of 2-(2-aminoethylam:'no) ethanol in ethanol and alcoholic potassium 
hydroxide will give a red or violet color with allethrin (or pyrethrins) if 
sulfur is added. The mechanism of the reaction is not known. Pure allethro- 
lone, allethrolone semicarbazone, chrysanthemum monocarboxylic acid and 
pyruvic aldehyde do not react under the conditions present. 



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PRODUCTION 

In November 1951 the rate of commercial production of allethrin was 
as follows: 

Pounds per Year 

Benzol Products 25,000 

Carbide and Carbon 20 to 25,000 

U. S. Industrial Chemicals none 

The future production was estimated to be: 

Benzol Products 100,000 

Carbide and Carbon 450 to 500,000 

U. S. Industrial Chemicals 100,000 

In the autumn of 1951 it was announced that Carbide and Carbon Chemicals 
Company was starting construction of a 6-million dollar plant at Institute 
(near Charleston), West Virginia for the production of allethrin. The first 
allethrin produced in this plant will be available in 1954. 

The commercial production of allethrin within a year of the announce- 
ment of its synthesis in the laboratory was an outstanding accomplishment 
and Haller (183) stated that industry should be congratulated for having 
done a fine job in so short a time. 

In April 1952 the U. S. Industrial Chemicals Company (191 ) announced that 
its new allethrin plant in Baltimore would be completed and in operation by 
July 1952. 

Benzol Products Company's plant at Piscataway, New Jersey in June 1952 
doubled its capacity for making allethrin pushing it to 100,000 pounds a 
year. The new capacity is an eight-fold increase in less than two years. — 
Anon. (41) . 

The allethrin produced since full scale production began more than one 
year ago is equivalent to approximately half of the high content pyrethrum 
imported during the same period. Such a consumption demonstrates conclusively 
its effectiveness when skillfully used. More than 12,000,000 allethrin 
aerosol bombs have been sold, and millions more are now being produced. — 
McLaughlin Gormley King and Company ( 119 ) and Anon. (38) . 

Availability 

The National Production Authority (141 ) at a meeting held January 30, 
1952 announced that no shortage of allethrin had developed so far. Military 
requirements for use in aerosol bombs have not been sufficient to limit 
availability for civilian use. 



Price 

The price of allethrin (100 percent basis) has declined from $55 a 
pound in 1950 to $32 a pound in August 1952. — Torpin (178 ) and Anon. (12) . 

PATENTS 

On February 8, 194-9 Schechter and LaForge ( 158 ) filed an application 
for a patent in the United States Patent Office for a process of making 
hydroxydiketones which can be cyclized to cyclopentenolones utilizable 
as intermediates in the synthesis of esters closely related to the pyrethrins 
and having their characteristic insecticidal properties. On November 13» 
1951 part of this application was granted as U. S. patent no. 2,574,500. 
This patent is dedicated to the free use of the people in the territory 
of the United States. 

U. S. Patent 2,603,652 granted Schechter and LaForge (159 ) on July 
15 i 1952 covers allethrin and similar esters. The methods of making 
allethrolone and analogous cyclopentenolones and of acylating these 
compounds are described. The knockdown and mortality of houseflies sprayed 
with solutions and aerosols of different esters are given. 

The foreign rights to this invention and to the inventions described 
in pending United States patents describing the synthesis of pyrethrin- 
like chemicals were acquired early in 1950 by U. S. Industrial Chemicals, 
Inc. (Anon. 16 ) . Corresponding applications have been filed in all major 
foreign countries including the United Kingdom, France, Australia, India, 
Brazil, Sweden, Pakistan, South Africa, and many others. 

SPECIFICATIONS 

Allethrin has been approved by the United States Department of Agri- 
culture for use in sprays and dusts in meat packing plants subject to the 
same restrictions that govern the use of pyrethrum. — Miller (128 t 129) . 

The U. S. Department of the Army (187 ) on December 6, 1950 issued 
military specification MIL- 1-1074-5 (0MC) for a 12-ounce insecticide aerosol 
dispenser. This specifies the use of 0.6 percent of allethrin (not less 
than 75 percent purity) for the type A insecticide or 0.4 percent of 
pyrethrins for the type B. 

On March 20, 1952 this specification was superseded by MIL-I-10745A 
( 189 ) which specifies a minimum content of 0.6 percent by weight of allethrin 
for the type I insecticide. The technical allethrin shall contain not less 
than 75 percent allethrin nor more than 8.0 percent total free acidity when 
calculated as chrysanthemum monocarobxylic acid. The material shall have 
not more than 0.5 percent dichlorodifluoromethane insoluble material as 
determined by the method described in Munitions Board Purchase Specification 
P-4-2 for pyrethrum extract. 



- 13 - 

Military specification MIL-I-11355 ( 188 ) dated August 14, 1951 for 
insecticide powder calls for a minimum of 0.30 percent by weight of allethrin 
for the type I insecticide. Other ingredients are 0.2 percent of pyrethrins, 
2 percent of sulfoxide, 5 percent of chloromethyl p-chlorophenyl sulfone, 
0.25 percent of antioxidant, 2.7 to 3.3 percent of conditioner and diluent 
(pyrophyllite) to make 100 percent. 

In July 1951 the Department of the Army revised purchase directives 
for the space spray covered by the Military Specification MIL- 1-10177 and 
substituted allethrin at0.15 percent in place of pyrethrins at .1 percent. 
During 1951 85,000 gallons of this allethrin space spray were purchased. 

The General Services Administration ( 190 ) on April 1, 1952 issued 
interim federal specification 0-1-511 (GSA-FSS) for a liquid space spray 
insecticide which calls for 0.15 to 0.18 percent by weight of allethrin, 
0.75 to 0.85 percent of piperonyl butoxide, 0.95 to 1.05 percent of DDT, 
0.04. to 0.06 percent of odor neutralizer and deodorized kerosene to make 
100 percent. 

ALLETHRIN IN AEROSOLS 

As soon as allethrin became commercially available it was tested as a 
replacement for pyrethrum extract in liquefied gas aerosols. 

Schroeder and Berlin (163 ) in 1950 reported that when applied in low 
pressure aerosols containing 15 percent of non-volatile material and 85 
percent of a mixture of Freon 11 and Freon 12 as a propellent, allethrin 
at 1.2 and 1.4 percent concentration was slightly superior to pyrethrins 
at the same concentration in both knockdown and kill. These aerosols were 
tested at an average dosage of 4- grams per 1000 cu. ft. Combinations of 
allethrin with piperonyl butoxide were about one-half as effective as simi- 
lar combinations of pyrethrins with piperonyl butoxide. The addition of 
2 percent of DDT did not change this ratio. Mixtures of allethrin and 
pyrethrins in combination with piperonyl butoxide showed only the addition 
effect of two materials having dissimilar synergistic relationships. 

Maughan e& .aJL (125) tested aerosol formulations containing allethrin 
or pyrethrins with DDT, MGK 264 and lethane 384. against 5-day old house 
flies of the CSMA strain. Four percent of lethane 384 adequately replaced 
0.3 percent of allethrin when 2-percent of DDT was present in both formu- 
lations. It was concluded that combinations of allethrin, lethane 384» 
and a synergist (MGK 264., n-propyl isome, Sulfoxide or piperonyl butoxide) 
will result in highly satisfactory aerosol formulations with or without pyre- 
thrins. 

Fales (67) at the 1951 mid-year meeting of the Chemical Specialties 
Manufacturers Association reported that allethrin had proved acceptable for 
use in aerosols, and may be used in combination with pyrethrins, or lethane. 
One very effective formula contains the usual DDT, 2 and 4. percent lethane, 
and 0.1 percent allethrin with no synergist. In a typical aerosol formula, 
containing 0.2 percent pyrethrins and synergists, part of the pyrethrins 
(as much as one-half) may be substituted by allethrin. Aerosol formulas 



- 14 - 

recommended for use on aircraft contain one or 1.2 percent pyrethrins. 
These combinations have been reformulated, using allethrin with a resulting 
increase in performance. 

As the result of these and other reports (cf . Moore 133 ) of favorable 
results of tests Rohwer ( 151 ) on October 26, 1950 announced that formulas 
containing allethrin were acceptable for use in gas-propelled aerosols. 

Shortly after this announcement was made it was reported (Anon. 23~25) 
that the army had okayed use of allethrin in low pressure aerosols, to 
replace hard-to-get natural pyrethrin insecticides, and was asking bids 
for more than 2 million low pressure aerosols to contain 0.6 percent alle- 
thrin, 2 percent DDT, 5 percent alkylated naphthalene, 7.2 percent deodor- 
ized kerosene, and 85 percent of a mixture of Freon 11 and Freon 12. 

In October 1951 it was announced that the Army would purchase 5 » 000, 000 
12-ounce aerosol bombs containing 0.6 percent allethrin through July 1952. 
At 2 grams per bomb this purchase requires 22,000 pounds of allethrin. 

Re snick and Crowell (148 ) of the U. S. Public Health Service in 1951 
reported that allethrin could be substituted for pyrethrum in the standard 
G-382 aerosol formulation without loss of effectiveness. The synergistic 
action of piperonyl butoxide and MGK 264 has not been as evident in formul- 
ations containing allethrin as in those containing pyrethrum extract. These 
tests were made on house flies in a modified Peet-Grady chamber. 

The U. S. Department of Agriculture has approved about 35 formulas 
containing allethrin for use under the licensing agreement governing the 
method of applying parasiticides covered by the Goodhue-Sullivan patent no. 
2,321,023 of June 8, 1943. These formulas usually contain from 0.10 to 0.4 
percent ofallethrin plus DDT, methoxychlor, lethane 384» Thanite, pyrethrins 
and various synergists and solvents in a 50:50 mixture of Freon 11 and Freon 12. 

STABILITY OF ALLETHRIN AND ITS FORMULATIONS 

When exposed to ultraviolet light for 5 hours (equivalent to 5 days 
exposure to mid-day sun) and to heat (110° F. for 24 hours and to 120° F. 
for an additional 48 hours) allethrin proved more stable than pyrethrins. 
These tests were made on mosquito larvae and house flies. An allethrin 
residue of 144 nig. per sq. ft. persisted for several months against house 
flies and when a synergist (piperonyl butoxide or sulfoxide) was added the 
amount of residue could be reduced to 28 mg. per sq. ft. — Granett .et .aJL. (86 ) . 

Fales et aX. ( 70 ) in 1951 reported that a high pressure aerosol con- 
taining 1 percent of allethrin held at room temperature for four months was 
equal in effectiveness against house flies to a freshly made sample. 

Fales et al. ( 68 ) also found that allethrin when formulated into a 
high pressure aerosol and stored for 15 months lost none of its effectiv- 
ness against house flies. There was no loss in effectiveness when a mixture 
of this material and DDT (in a low pressure aerosol) was stored for 10 months. 
Allethrin in kerosene sprays showed no loss in effectiveness after 6 months 
storage. 



- 15 - 

Fales and associates ( 71 ) also reported that in storage tests with 
sprays and aerosols containing the ester made with the natural d- trans 
acid there was no loss in effectiveness against house flies. 

Schreiber (162 ) found that the decomposition, in thin layers, of 
pyrethrins was reduced to about one-half when mixed with at least an equal 
weight of MGK 264 and irradiated under equal conditions with a mercury 
vapor quartz lamp (Hanovia Alpine) for six hours at temperatures not 
exceeding 135° F. The irradiation described produced a vivid greenish 
yellow fluorescence in accordance with Stokes law. A similar though 
slightly smaller protective effect was obtained in the irradiation of 
allethrin. In each case the degree of decomposition was checked by the 
Seil method for the determination of pyrethrin I since the alkaline treat- 
ment required tends to decompose also part of MGK 264 thus rendering a 
determination of^pyrethrin II quite vague. 

USE OF SYNERGISTS WITH ALLETHRIN 

Allethrin in aerosols is not activated by the usual pyrethrin syner- 
gists to the extent that the pyrethrins are (Fales 67) . The same observa- 
tion holds true for sprays. This lack of a good allethrin synergist has 
stimulated a great deal of testing of compounds for possible synergistic 
value but to date nothing outstanding has been found. Stage (169) in 1951 
reported that approximately 150 compounds have been tested at Corvallis, 
Oregon to determine whether they enhance the effectiveness of allethrin 
when used as a residual treatment against adults of Aedes vexans (Meig.), 
and A» stlcticus (Meig.). Only 16 of the materials showed some promise a'j 
synergists, and none of these were especially outstanding. 

MGK 264 

MGK 264, which is N-2-ethylhexyl bicyclo- (2.2.1 )-5~heptene-2, 3"dicarbox- 
imide, is a valuable synergist when combined with allethrin and pyrethrins 
for roach control in both aerosols and liquid sprays. In aerosols MGK 264. 
may be used at ratios of five to 15 to lpart pyrethrins or allethrin. — Moore (132 ) 

With the use of MGK 264 with allethrin, aerosol formulations can be 
arrived at which are at least equal in effect and often superior to the 
tentative official test aerosol of CSMA not only against flies but also 
against roaches. Such formulations may contain, for example, 2-3 percent 
of DDT, 2 percent MGK 264, and either from 0.10-0.15 percent each of alle- 
thrin and of pyrethrins or 0.25 percent of allethrin or 0.20-0.25 percent of 
pyrethrins. Also in experimental dusts for agricultural use combinations of 
allethrin and 264 have proved effective, for example, against flea beetle, 
cabbage worm, and small tarnished plant bug. — Schreiber (16.2) . 

n- Propyl isome 

n-Propyl isome is a condensation product of isosafrole and di-n-propyl 
maleate (Synerholm and Hartzell, Boyce Thompson Inst. Contrib. 14: 85-86, 
1945. U. S. patent 2,431,845, Dec. 2, 1947). According to Penick and Com- 
pany (144 ) it is a synergist for allethrin. 



- 16 - 



sulfoxide 



This isthe name given to n-octyl sulfoxide of isosafrole by Penick and 
Company. It was formerly written "sulfox-cide." 

Starr ( 170 ) in 1950 reported that in preliminary tests, a 16 day old 
residue of 44. mg. of allethrin and 220 mg. of sulfoxide per square foot on 
kraft paper, gave a knockdown of house flies of more than 95 percent in 30 
minutes and a kill of better than 95 percent in 24 hours. Exposure was 
limited to two hours. After aging 37 days, the knockdown was better than 
95 percent in two hours, but the kill dropped to 35 percent. Doubling the 
quantities of materials in the residue increased the time of effectiveness 
from 16 days to 11 weeks. 

According to Starr ( 171 ) a high grade emulsion can be made using 
allethrin and sulfoxide. Starr also gave the following formulas for aero- 
sols containing allethrin. 

Aerosol formulation 105 contains: 

Allethrin ---------------1 percent 

Sulfoxide (n-octyl sulfoxide of isosafrole) - - 5 percent 
Ultrasene ---------------4 percent 

Freon 11 --------------- 45 percent 

Freon 12--------------- 4.5 percent 

A formula containing: 

Allethrin --------------- 0.2 percent 

DDT 2 percent 

Sulfoxide ---------------1 percent 

was above CSMA's T0TA in both 15 minute knockdown and 24 hour kill at either 
3 or 4. grams per 1000 cubic feet. 

Piperonyl butoxide 

This synergist contains as its principal constituent alpha-[2-(2- 
butoxyet ho xy)-ethoxy~l -4 »5-methylenedioxy-2-propyl toluene. 

Schroeder and Berlin (162) in 1950 reported that when applied in low 
pressure aerosols containing 15 percent of non-volatile material and 85 
percent of a mixture of equal parts of Freon 11 and Freon 12 as a propellent, 
allethrin at 1.2 and 1.4 percent concentration was slightly superior to 
pyrethrins at the same concentration in both knockdown and kill. These 
aerosols were tested at an average dosage of 4- grams per 1000 cu. ft. Com- 
bination of allethrin with piperonyl butoxide are about one-half as effective 
as similar combinations of pyrethrins with piperonyl butoxide. The addition 
of 2 percent of DDT did not change this ratio. Mixtures of allethrin and 
pyrethrins in combination with piperonyl butoxide showed only the additive 
effect of two materials having dissimilar synergistic relationships. 



- 17 - 

Against resistant house flies in Florida allethrin and pyrethrins plus 
piperonyl butoxide were moderately effective early in 1950, but by the end 
of the season none of them provided satisfactory control. — Wilson et al. ( 194 ) . 

Incho and Greenberg ( 104 ) tested the synergistic effect of piperonyl 
butoxide when mixed with pyrethrins and with its four constituents separately 
and also with allethrin and allethrolone esters against house flies by the 
turntable method. By the use of a value representing relative synergistic 
effect it was shown that the cinerins exhibited a somewhat greater degree of 
synergism in a combination with piperonyl butoxide than did the pyrethrins, 
although pyrethrins I and II showed superior effectiveness to the corresponding 
cinerins, both alone and in combination with piperonyl butoxide. 

Since none of the separated active components of pyrethrum showed greater 
synergistic activity than the standard pyrethrum extract, it may be concluded 
that no one of the components of pyrethrum contributed the major portion of 
the synergism found with combinations of piperonyl butoxide and pyrethrins, 

Although optical and geometric isomerism in the acid portion of the 
molecule have a marked influence onthe insecticidal effectiveness of alle- 
throlone esters of chrysanthemum monocarboxylic acid when used alone or in 
combination with piperonyl butoxide, they have little effect on comparative 
synergistic activity. 

m-Nitrobenzamides 

Gertler et aj.. (83 ) in 1952 reported the results of tests of certain neta-nitro- 
benzamides for synergistic action in allethrin fly sprays. The concentration 
was 0.5 nig. allethrin and 20 mg. adjunct per ml. and all tests were made 
against house flies by the Campbell turntable method. Acetone was used as 
an auxiliary solvent to increase the solubility of the amides in kerosene. 
Ten of 22 materials caused significant increase in toxicity. These were 
the N,N-dibutyl, diethyl, diisobutyl, diisopropyl, dimethyl, and dipropyl 
and the N-isobutyl and isopropyl derivatives of meta-nitrobenzamide; 1, 
meta-nitrobenzoylpiperidine and meta-nitro-N-propylbenzamide. The adjuncts 
alone showed negligible toxicity. 

Comparative value of synergists for allethrin 

The comparative effect of piperonyl butoxide, n-propyl isome, and MGK 
264 in sprays oontaining either allethrin or pyrethrins in the proportion 
of 10 times as much adjunct as insecticide was determined by Gersdorff et 
.§,1. ( 81 ) in tests against the house fly, by the turntable method. The 
joint action of each of the three pyrethrum synergists with allethrin was 
of the synergistic type. 

Piperonyl butoxide synergized pyrethrins more effectively than it did 
allethrin, the mixed spray with the natural insecticide being about 13 times 
as toxic as pyrethrins and mixed spray with the synthetic insecticide being 
but two and one half times as toxic as allethrin. The synergistic effect was 



- 18 - 

therefore five times as great with pyrethrins as it was with allethrin. 
Because of the greater toxicity of allethrin, however, this disparity was 
decreased somewhat, and mixed sprays containing the synthetic product were 
about half as toxic as those containing the natural product. 

The synergistic effect of n-propyl isome was about three times as 
great with pyrethrins as with allethrin, since the pyrethrins mixture was 
but little more toxic than the allethrin mixture. The allethrin mixture 
was nearly as toxic as the mixture of allethrin and piperonyl butoxide, 
but less than half as toxic as the mixture of pyrethrins and piperonyl 
butoxide. 

Synergist MGK 26A was not so effective a synergist as piperonyl 
butoxide, increasing the effectiveness of the spray by two-thirds when 
included with pyrethrins and by one- third when included with allethrin. 
The synergistic effect was therefore one and one-fourth times as great with 
pyrethrins as it was with allethrin. However, because of the greater 
toxicity of allethrin the mixture containing allethrin was about twice as 
toxic as that containing pyrethrins. 

The relative effectiveness of the insecticidal materials, with and 
without a synergist, is in the following ascending order, whether the 
evaluation is based on the principal toxicant only or on the insecticide 
equivalent: (l) pyrethrins, (2) pyrethrins plus synergist MGK 26A, (3) 
allethrin, (A) allethrin plus synergist MGK 264, (5) pyrethrins plus n- 
propyl isome, allethrin plus n-propyl isome, and allethrin plus piperonyl 
butoxide, and (6) pyrethrins plus piperonyl butoxide. The last mixture 
was 17 times as effective as pyrethrins by the first criterion and 13 times 
by the second. 

Allethrin caused slightly slower knockdown than did natural pyrethrins. 
However, all sprays caused complete or nearly complete knockdown at the 
low concentration of 0.25 mg. of insecticide per milliliter of kerosene. 

Piquett ( 14.5 ) in 1949 reported that piperonyl butoxide, piperonyl 
cyclonene and n-propyl isome increased the toxicity of allethrin to adult 
male American cockroaches when applied as dusts containing 0.6 percent of 
allethrin and 3 percent of the synergist. Sesame oil was ineffective in 
synergising allethrin. Allethrin alone killed 65 percent of the roaches 
in A days, pyrethrins alone killed 83 percent and the mixtures of allethrin 
with the effective synergists killed 75 to 87 percent. 

Starr ( 171 ) in 1950 gave formulas for the use of MGK 26/,., n-propyl isome 
and sulfoxide with allethrin. Allethrin mixed with n-propyl isome (l:5)» 
MGK 26^ (1:10), sesame oil extractives (l:3.75)> and piperonyl butoxide 
(1:8) and tested against house flies by the Peet-Grady method was in general 
less effective than similar mixtures of pyrethrins with the synergists. 
MGK 26A appeared to be almost equally as effective with pyrethrins at the 50 
percent mortality level. The difference in effectiveness between allethrin 
and pyrethrins with synergists appears to be more pronounced against German 
roaches than against house flies. In surface deposit tests on glass plates 
about 3 times the dosage of allethrin with piperonyl butoxide is required to 
obtain the mortality of roaches given by the pyrethrins-butoxide combination. 



- 19 - 

Jones et al . ( 107 ) in 1950 reported on the first thorough study of 
allethrin in combination with the four commercially available pyrethrum 
synergists. In Peet-Grady tests with house flies they found that with sesame 
oil extractives it required somewhat less than twice, with n-propyl isome 
about twice, and with piperonyl butoxide over twice as much allethrin with 
synergist as pyrethrins with synergist to produce 50 percent mortalities. 
Synergist 26^. appeared to be almost as effective with allethrin as with 
pyrethrins at the 50 percent mortality level. 

They also reported that against grain insects such as the confused 
flour beetle and the rice weevil, surface deposits of allethrin with piperonyl 
butoxide may be less than one-third as effective as those of pyrethrins and 
piperonyl butoxide. In dusts against certain truck crop insects a combin- 
ation of allethrin with piperonyl cyclonene was- generally less effective 
than that of pyrethrins with piperonyl cyclonene s, but the difference in 
effectiveness varied greatly with the insect species. For example, against 
Mexican bean beetle adults and larvae the allethrin- cyclonene dust gave 
almost the same mortality as the pyrethrins-cyclonene dust, while against 
squash bug adults and nymphs the allethrin combination was very much less 
effective than the pyrethrins combination. 

In tests with high-pressure aerosols against house flies piperonyl 
butoxide, n-propyl isome, and sesame oil extractives all showed synergism 
with allethrin. There was considerable recovery of flies knocked down with 
sesame oil extractives formulation. The formulas oontaining n-propyl isome 
acted similarly with allethrin and with natural pyrethrins. The MGK 26^ 
formulas appeared to give slightly better kill when allethrin was used. The 
knockdown was lower, but the mortality was the same, when piperonyl butoxide 
was used with allethrin. — Fales et al. (70). 

Di-n-butyl hexahydrophthalate and dibutyl cis- bicvclo^ 2.2.1 ]-heptene- 
2,3-dicarboxylate (dibutyl carbate) as synergists produced better results 
with allethrin than with pyrethrins when tested against the deerfly. — Hoffman 
and Lindquist (103 ) . 

The comparative effect of sulfoxide and 3,4-methylenedioxybenzyl n-propyl 
ether in oil sprays containing either allethrin or pyrethrins in the propor- 
tion of five times as much adjunct as insecticide was- determined by Gersdorff 
et al . (82) in tests against the house fly bythe turntable method. The two 
pyrethrum synergists also synergized allethrin but to a lesser degree than 
they did pyrethrins. The intensity of synergism with sulfoxide was £.7 and 
with the benzyl propyl ether 1.3 as great in the pyrethrum mixtures as in 
the allethrin mixtures. The mixture of sulfoxide and pyrethrins wasl0.8 as 
toxic as pyrethrins, whereas the mixture of sulfoxide and allethrin was but 
2.3 as toxic as allethrin. The mixture of the benzyl propyl ether and 
pyrethrins was 1.8 as toxic as pyrethrin, whereas the mixture of the benzyl 
propyl ether and allethrin was 1.4. as toxic as allethrin. However, when con- 
sideration is given to the greater toxicity of allethrin as compared with 
pyrethrins as well as synergistic effect, the relative effectiveness of the 
insecticidal materials falls in the following ascending order, whether the 



- 20 - 

evaluation is based on principal toxicant only or on insecticide equivalent: 
(l) pyrethrins, (2) pyrethrins plus the benzyl propyl ether, (3") allethrin, 
(A) allethrin plus the benzyl propyl ether, (5) allethrin plus sulfoxide, 
and (6) pyrethrins plus sulfoxide. The last-named mixture is nearly 12 
times as toxic as pyrethrins on the first basis and nearly 11 times on the 
second. Knockdown of flies was of high order for all mixtures. 

Laboratory tests against house flies indicate that the pyrethrum syner- 
gists sulfoxide, n-propyl isome, and MGK 26^. can be substituted for piperonyl 
butoxide in the MIL-8TD-129 or Type II Interim Federal Specification 0-1-511 
space spray. Substitution can be made at equal concentration levels but 
sulfoxide and n-propyl isome require auxiliary solvents. — Nelson et, al. ( 14.2 ) , 

In tests against house flies by the Peet-Grady method, four synergists 
were tested at a concentration of 0.80 percent by weight in deodorized 
kerosene solutions of allethrin (0.16 percent). It was concluded that there 
are no significant differences between piperonyl butoxide, isome, sulfoxide 
and sulfone. — Calsetta (5/0 . 

In tests of piperonyl butoxide and sulfoxide as synergists for pyre- 
thrins and allethrin against the flour beetle Hewlett ( 102 ) found sulfoxide 
to be six times as potent as piperonyl butoxide when used with pyrethrins 
and 1.8 times as potent when used with allethrin. In comparisons of insecti- 
cides pyrethrins and allethrins were equally toxic. 

Hewlett (101) in 1952 reported that 5 percent of piperonyl butoxide 
synergized 3.5 percent of allethrin in solution in Shell oil P-31 in tests 
on the flour beetle Tribolium castaneum (Hbst.). The beetles were either 
exposed on films of the insecticides on filter paper at 25° C. or were 
directly sprayed and afterwards kept at 25° C. The response in the groups 
of beetles was determined six and nine days after the start of their exposure 
to insecticide. 

ALLETHRIN STEREOISOMERS 

Allethrin is a mixture of 8 stereoisomers which differ in insecticidal 
value. This fact should be kept in mind in evaluating reports of its tests 
against various species of insects. In this respect commercial allethrin 
is analogous to crude benzene hexachloride from which 5 of the 8 theoreti- 
cally possible stereoisomers have been isolated. The gamma isomer of BHC 
accounts for practically all the insecticidal value of the product, whereas 
the beta isomer is responsible for the chronic toxicity of BHC to mammals. 
By separating the gamma isomer of BHC from the crude mixture a product 
(lindane) of superior insecticidal value has been obtained and at the same 
time the less desirable properties of the other isomers have been left 
behind. Although no simple procedure for separating the isomers in commer- 
cial allethrin isknown, such an achievement is not impossible. 



- 21 - 

The 8 isomers in allethrin are: 

cis form of 1-acid esterified with 1-allethrolone 

it ii ii j- a cid " " d-allethrolone 

" " " d.-acid " " .1-allethrolone 

» " " £-acid " " d-allethrolone 

trans form of 1-acid esterified with 1-allethrolone 

." " " 1-acid n " d-allethrolone 

tt n n d-acid M " .1-allethrolone 

w ii « d-acid " " d.-allethrolone 

Schechter and associates inthe Division of Insecticide Investigations, 
Bureau of Entomology and Plant Quarantine are now working on the separation 
of these isomers in order to determine their individual activities to dif- 
ferent species of insects. 

A step in this direction has been accomplished by the separation of 
crystalline allethrin, m.p. 50. $-$1° C, from molecularly distilled allethrin 
by cooling to about U° C., or by low temperature crystallization from low 
boiling petroleum ether. This crystalline product called the alpha-dl-trans 
isomer must consist of one of the racemic ester pairs, d -trans acid with 
d-allethrolone plus 1- trans acid with 1-allethrolone, or d-trans acid with 
1-allethrolone plus 1- trans acid with ^1-allethrolone; the beta-dl-trans 
isomer consists of the other pair. Entomological tests on house flies indi- 
cate the alpha-dl-trans isomer to be less effective and the beta-dl-trans 
isomer to be more effective than allethrin. — Schechter et al. ( 160 ). 

In 194-9 Gersdorff (76 ) reported that the d-chrysanthemum mono car boxylic 
acid ester of synthetic 2- ( 2-butenyl )-£- hydroxy- 3~roethyl-2-cyclopenten-l-one 
(probably a geometric isomer of cinerolone) was as toxic as natural cinerin 
I, about one and one- half times as toxic as the mixture of "pyre thr ins" con- 
tained in the ordinary pyr ethrum-kero sene extract. The replacement of the 
2-butenyl side chain of these compounds with the allyl group was accompanied 
by a nearly 5~fold increase in toxicity whether the acid component was the 
dextro natural one or a racemic cis or trans synthetic one. The allyl com- 
pound with the natural acid component was the most toxic of any of the known 
pyrethroids, 6 to 7 times as toxic as the mixture of "pyrethrins." No dif- 
ference in toxicity was found between the compounds of the cis and trans 
forms of the acid component for both classes of compounds, the 2-butenyl and 
the allyl. (However, see more recent work below). For both classes the 
ester with the natural dextro acid component was about 3.8 times as toxic as 
an ester with a synthetic racemic acid component. The completely synthetic 
isomers of cinerin I were about 0.39 times as toxic as the mixture of 
"pyrethrins." The completely synthetic allyl compounds were about 1.8 times 
as toxic as the "pyrethrins." The effect of other changes in chemical 
structures on toxicity was determined. Knockdown effect was of high order 
for all the compounds. 



- 22 - 

The marked difference in insecticidal value of the allethrin stereo- 
isomers due to optical activity was demonstrated by Gersdorff (77) . He 
reported that the ester made from synthetic allethrolone and natural d- 
trans chrysanthemum acid was 6 times as toxic as the natural pyrethrins 
against house flies, whereas the completely synthetic ester (synthetic 
allethrolone esterified with synthetic dl-cis- trans chrysanthemum acid) 
was 3 times as toxicj that is, the optically active isomer was twice as 
toxic as the optically inactive ester. 

More recently Gersdorff and Mitlin ( 7 , 9 ) reported that the dl- trans 
fraction of allethrin was 1.56 as toxic as the dl-cis fraction. The toxic 
action of the two fractions when applied in mixtures was identified as 
similar action. The trans fraction was 1.33 and the cis fraction 0.85 as 
toxic as this sample of allethrin. On this basis the allethrin used in 
this study contained about 69 percent cis isomers and about 31 percent trans 
isomers. A crystalline compound, separated from the trans fraction, was 
only 0.35 as toxic as allethrin and constituted 8 percent of that insecticide. 
The remainder of the trans f raction was 1.69 as toxic as allethrin and 
constituted 23 percent of that insecticide. It is deduced that half of each 
of these portions of the trans fraction is relatively nontoxic and that one 
of the remaining two isomers, d- trans acid with d-allethrolone and .d-trans 
acid with 1-allethrolone, is 0.70 as toxic and the other 3.38 as toxic as 
allethrin. All the separated constituents possessed high knockdown value. 
All these tests were made on the housefly by the Campbell turntable method. 

Elliott (65) has discussed the relationship of chemical constitution 
to the insecticidal activity of substances related to the pyrethrins. 



ANALOGS OF ALLETHRIN 

When the high insecticidal value of alJebhrin and the method of its 
synthesis were announced, chemists prepared analogous compounds by combining 
synthetic chrysanthemoyl chloride with substituted cyclopentenolones. In 
Japan Inoue and associates ( 106 ) synthesized lower alkyl- and alkenyl cinerin 
homologs in this way. They also synthesized fifty kinds of pyrethroids from 
aromatic, aliphatic, terpenic alcohols, dialkylamino-ethylalcohols, monoalkyl- 
ethylene alcohols and chrysanthemoyl chloride in an analogous manner. Insec- 
ticidal activity of these compounds was tested against the common house fly 
in kerosene space spray. 

Nagasawa ejt ja|L. (136 ) prepared the ethyl analog of allethrin, called 
ethythrin. The toxicity of allethrin to pupae of the common house mosquito 
( Culex pjpiens var. pallens Coquillett) when applied in water emulsion was 
approximately 10 times that of ethythrin. From the test results of a 1:2 
mixture of allethrin and ethythrin it was concluded that these two toxicants 
act similarly on mosquito pupae. 

Matsui (124.) i n Japan and LaForge, Green, and Schechter at Beltsville 
have synthesized an insecticidal ester named furethrin of the type of alle- 
thrin but with a 2-furfuryl side chain. The procedures follow those employed 
in the synthesis of alDethrin with furfurylacetone as a starting material. 



- 23 - 

Tests on house flies by Gersdorff and Mitlin (80 ) show that furethrin 
compares favorably with allethrin in toxicity to house flies. '0 f all com- 
pounds analogous to allethrin, furethrin is the most promising. In tests 
against the house fly by the turntable method furethrin (synthesized in 
Beltsville) had a relative toxicity of 1.1 as compared to a toxicity of 1 
for the pyrethrins. The ester made by combining natural (d - trans ) chrysan- 
themum monocarboxylic acid with furethrolone had a relative toxicity of 1.9. 
Both products had high knockdown value. 

Gersdorff and Mitlin ( 78) tested the insecticidal value of certain 
allethrin analogs to house flies. Five substituted cyclopentenolones were 
acylated with a mixture of cis and trans dl- chrysanthemum monocarboxylic 
acids and the purified esters dissolved in refined kerosene for testing by 
the Campbell turntable method. Two compounds, each with one chlorine atom 
introduced into the allyl side chain characteristic of allethrin, were 
one and one-half times as toxic as pyrethrins. No difference in toxicity 
was demonstrated whether the attachment was on the second or third carbon 
atom. A compound with a triple bond in the side chain (2-butynyl) of the 
cyclopentenolone component was about three-fourths as toxic as pyrethrins. 
A compound with a chlorine atom introduced at the third carbon atom in the 
2-butenyl side chain was one-fifth as toxic as pyrethrins. A compound with 
an allyl side chain attached to the carbon atom in position 5 of the cyclo- 
pentenolone nucleus as well as in position 2 was about two-fifths as toxic 
as pyrethrins. 

LaForge et al . (112 ) in 1952 reported that all allethrin type esters of 
a number of cyclopropanecarboxylic acids were less toxic than allethrin to 
house flies by the turntable method. The most toxic ester, that of dl- 
dihydrochrysanthemum monocarboxylic acid, was as toxic as natural pyrethrins. 
Since the 1 -trans- acid ester was but 2 percent as toxic as the d - trans-acid 
ester, configuration in the acid component is of great importance with res- 
pect to toxicity. The toxicity ratio of the type I ester to the type II 
ester for the allethrin-type esters of the natural d-trans- chrysanthemum acids 
was U»L to 1, which is about the same as for pyrethrins I and II and dner- 
ins I and II. 

TOXICOLOGY 

Starr .et al . (172) inl950 reported that chronic toxicity tests on white 
rats showed allethrin to be nontoxic when used as a spray or incorporated 
with food. The allethrin tested was a technical grade product manufactured 
by the Carbide and Carbon Chemicals Corporation. A diet containing 0.2 per- 
cent of allethrin had no noticeable harmful effect on rats or their offspring 
over a period of 2A weeks and at that time control and experimental rats were 
approximately the same size. Inhalation of 1 percent allethrin aerosol sprays 
in large amounts did no apparent damage to rats during 22 weeks 1 exposure, 
30 minutes per day, 6 days per week. The rate of growth of new-born rats 
subjected to the treatment was the same as the control group. In none of 
the experimental animals was any abnormality found which could be correlated 
with the application of allethrin. 



- 24 - 

At the June 1950 meeting of the Chemical Specialties Manufacturers 
Association, Inc., Starr et al. ( 17 . 3 ) presented additional data on the 
toxicity of allethrin to rats. After feeding for 4.1 weeks on dog-food 
containing 0.2 percent of allethrin (dosage approximately 200 mg./kg. per 
day) rats were in good condition with body weight equal to controls. 
All female rats gave birth to at least two normal litters. In aerosol 
inhalation tests the rats were sprayed with 800 g. per 1000 cu. ft. and 
exposed 30 minutes per day six days a week in their regular cages. 
During a period of 39 weeks none of the experimental rats including 48 
new born rats were harmed by the aerosol which contained 1 percent of 
allethrin, 9 percent of petroleum distillate (Eayol D), 45 percent of 
Freon 11 and 45 percent of Freon 12. Another aerosol formula contained 
1 percent of allethrin, 5 percent of sulfoxide, 4 percent of petroleum 
distillate (Ultrasene), 45 percent of Freon 11 and 4-5 percent of Freon 12. 
Eight rats were sprayed with this formula as in the other test, except 
that 1600 g. per 1000 cu. ft. were tested in addition to the 800 g. 
exposure. There were no deaths in seven weeks and weight gains were normal. 
A total, of 40 rats which were representative of the experimental animals ex- 
posed to allethrin in the diet or aerosol were sacrificed at various times 
from one to eight months after the start of the experiments. Autopsy 
showed no visible damage or gross pathology in any of the internal organs. 
Microscopic examination of the organs was made. In none of the experimental 
animals was any abnormality found which could be correlated with the insecti- 
cide treatments. 

Carpenter .et al. (56 ) of the Mellon Institute of Industrial Research 
in October 1950 reported on the comparative acute and subacute toxicities 
of allethrin and pyrethrins. 

Two separate inhalation studies on aerosols containing 1 percent by 
weight of allethrin or of pyrethrins, 9 percent of peanut oil and 90 percent 
of Freon 12 were carried out at concentrations in excess of 50 g. of total 
formulation per 1000 cu. ft. of space. 

In the first study laboratory-produced allethrin and the comparative 
aerosols casued no detectable injurious effects on rats exposed twice daily 
for 30-minute periods up to a total of 85 such periods within 67 calendar 
days. In a second similar study a sample representing commercially produced 
allethrin (92 percent allethrin) caused no injury to rats or dogs receiving 
40 exposures, each of 30 minutes duration, within 27 calendar days. 

Single 30 minute exposures of rats to concentrations of aerosols of 
commercial allethrin and pyrethrins on the order of 350 times the level used 
for the repeated exposures caused no visible damage, nor did they depress 
weight gain during a subsequent 14-day observation period. 

A fog of commercial allethrin produced by a vaponefrin nebulizer was 
lethal to one of 10 rats in a two-hour exposure at a concentration of 19 
mg./l., and only four of 10 succumbed in a four-hour exposure to 13.8 mg./l. 
These massive concentrations of allethrin < are respectively 10,000 and 7,000 
times the amounts that would be present in the aerosols utilized in freeing 
aircraft from insects. The extreme viscosity of an 84 percent pyrethrin 
concentrate and its unavailability made comparison by this method impossible. 



- 25 - 

The single dose acute oral LD-50' s of commercial allethrin for 
rodents fed 20 -percent dilutions in deodorized kerosene are as follows: 
mice 0.48, rats 0.92, and rabbits 4.29 g./kg. Two different samples of 
purified pyrethrins, 20 percent in petroleum distillate, gave LD-50 values 
of 0.82 and 1.87 g./kg. for rats. 

The LD-50 of undiluted commercial allethrin for rabbits by the per- 
cutaneous route is 11.2 ml. /kg. Dilution in deodorized kerosene markedly 
increases toxicity by skin penetration, but dimethyl phthalate appears not 
to aid penetration. 

Undiluted commercial allethrin and dilutions in deodorized kerosene 
are harmless to rabbit eyes, but they cause moderate erythema of the clipped 
skin of the rabbit belly when applied in single or repeated applications. 
Drill cloth impregnated with this allethrin at the rate of 4 g. per square 
foot caused marked erythema of the hair-free trunk of rabbits when worn for 
three days. Subsequently these reactions subsided even though the impreg- 
nated bands were reapplied twice each week during a 21-day period of wear. 
No systemic injury, as judged by weight changes, resulted, and all skin 
reactions had subsided in this interval. 

Guinea pigs could not be sensitized by a course of eight intracutaneous 
injections of a 0.1-percent dispersion of allethrin in 3.3~percent -propylene 
glycol in isotonic sodium chloride solution followed by a 21-day incubation 
period before retest. 

Carpenter .et al. concluded that commercial allethrin is of the same 
relative order of toxicity as pyrethrins and that it may be used safely as 
an insecticide in sprays and aerosols. 

Lehman ( 115 ) of the Food and Drug Administration in 1951 stated that 
the acute toxicity of allethrin to the rat (approximate LD-50 mg./kg.) was 
680 and that of the pyrethrins was 200. In these tests the dosages were 
administered by stomach tube to fasted animals. Allethrin causes tremors 
and convulsions. The onset of the symptoms of poisoning is within 30 min- 
utes, the duration 6 hours. Fatalities appear to be rare 24 hours after 
poisoning. Death is due to respiratory paralysis. 

Ambrose and Robbins (43) of the Western Regional Research Laboratory 
of the U. S. Department of Agriculture have reported a study of the com- 
parative toxicity of pyrethrins and allethrin. 

Purified pyrethrins containing 86.2 percent total pyrethrins and syn- 
thetic allethrin containing 93.6 percent allethrin administered gastrically 
or subcutaneously to rats in doses of 2.6 and 1.6 gm./kg., respectively, 
produced no toxic reactions. When rubbed into the skin of rats in amounts 
of 50 mg. daily for 30 days, they produced no local reactions. On albino 
guinea pigs and on the anterior cubital surface of three humans, purified 
pyrethrins or allethrin produced no signs of local irritation. With less 
pure allethrin some transitory skin irritation was observed. Albino guinea 
pigs were not sensitized by topical application or intracutaneous injection 
of purified allethrin. The effect of prolonged oral ingestion of one sample 



- 26 - 

of commercial allethrin and a purified sample of commercial allethrin, 
assaying 72. L and 92 percent allethrin, respectively, was studiec in rats on 
diets containing 78, 156, 312, 625» 1225, 2500 and 5000 ppm of the respective 
allethrin samples. Rats on the diet containing 5000 ppm commercial alle- 
thrin showed a slight decrease in growth as compared with rats on the diet 
containing the same concentration of purified allethrins. Hematological 
findings on rats on the various dietary levels of the two allethrin samples 
were indistinguishable from those of the controls. From these preliminary 
observations it is concluded that purified allethrin is no more toxic than 
purified pyrethrins. The toxic reaction observed after topical application 
or after prolonged oral ingestion is undoubtedly due to impurities. More 
extensive studies on chronic toxicity are in progress. 

Lehman (116 ) has expressed the opinion that the pyrethrins in combin- 
ation with any of the three activators, piperonyl butoxide, n-propyl isome 
and MKG 26^. appear to be among the safest of insecticides. "V/e have yet to 
demonstrate adverse effects in our animals on chronic feeding experiments 
at levels considerably above what might be expected as contaminants of food 
when these materials are properly used. Allethrin is showing every indication 
of being in the same category, toxicologically, as the natural pyrethrins. 
The dermal and acute oral toxicities, and the preliminary chronic feeding 
data coincide very well with our results on the natural products." 



CLASSIFICATION OF INSECTS AGAINST WHICH ALLETHRIN 

HAS BEEN TESTED 

The literature records the results of tests of allethrin against 67 
identified species of insects and other arthropods belonging to 60 genera, 
37 families and 10 orders. In addition allethrin has been tried against 
many insects unidentified as to species such as ants, lice, and mosquitoes. 

In the following summary of these tests the families and genera of 
insects are placed alphabetically under the orders which are arranged 
according to increasing complexity of structure from Orthoptera to Hymenoptera. 

0RTH0PTERA 

Blattidae 

BlatteHa germanica (L.), the German cockroach 

Allethrin at 100 and 200 mg. per 100 ml. was inferior to pyrethrins in 
knockdown in 1 hour and mortality in 2k hours. Stoddard and Dove ( 177 ) . 

Allethrin was inferior to pyrethrins. In tests on roaches the addition 
of piperonyl butoxide, MGK 264 and two homologs thereof to allethrin increased 
the kill.— Moore (13A ). 



- 27 - 

When tested in oil solution by the direct spray method allethrin was 
1/2 as effective as the pyrethrins in knockdown and kill. When tested by 
the settling mist method at concentrations of 0.10 and 0.20 percent, 
allethrin was nearly ecuivalent to pyrethrins in knockdown and kill. — Nash 

Cm). 

When tested in Deobase solution by the settling mist method allethrin 
was slower in knockdown than pyrethrins and caused 0.7 to 0.9 as much 
mortality of female roaches in 4.8 hours. — Granett .££ .al. ( 86) . 

Periplaneta americana (L.), the American cockroach 

An aerosol containing 1 percent of allethrin applied at a dosage of 
35 g./lOOO cu. ft. killed no adult females in 5 days and only 12 percent of 
large nymphs; pyrethrins killed 4-2 percent of the adult females and 18 percent 
of tne large .lymphs. The roaches were confined in a pen on the floor of a 
p eet-0rady chamber.— Fales et al. (70). 

Allethrin was inferior to pyrethrins. — Moore ( 134. ) . 

By the injection method the 'approximate LD-50 for female nymphs was 
3.25 micrograms per gram for allethrin, and 1.375 micrograms per gram for 
pyrethrins indicating the natural material to be about 2.4- times as toxic 
as allethrin when tested in this way. — Bishopp (4.8) . 

When tested in Deobase solution by the settling mist method allethrin 
was 1/4 to 1/6 as toxic as pyrethrins to female roaches; 0.2 percent pyre- 
thrins caused the same knockdown in 30 minutes and the same kill in 4 days 
as 1.2 percent allethrin. — Granett .et .al. (86). 



THYSAN0PTERA 

Thripidae 

Hercinothrips femoralis (Reut.), the banded greenhouse thrips 

In greenhouse tests aerosols of allethrin and of pyrethrins gave 
equally good control. — Roark ( 149 ). 

H0M0PTERA 

Aleyrodidae 

Aleurocanthus woglumi Ashby, the citrus blackfly 

In laboratory tests allethrin in Deobase was slightly superior to a 
similar solution of pyrethrins. — Bishopp (48) . 



- 28 - 

Aphidae 

Aphis f abae Scop., the bean aphid 

Allethrin at the rate of 0.06 pound per 100 gallons of water plus an 
equal quantity of Dreft killed 100 percent of the aphids; pyrethrins did 
likewise. Dreft alone killed only 2 percent of the aphids. — Bishopp (48) . 

In laboratory spraying tests against adult apterous viviparous 
parthogenetic females pyrethrins were about 14 times as toxic as allethrin. 
—Elliott et .gl . (66) • 

Aphis gossypii Glov., the cotton aphid 

In tests against the cotton aphid 1 and 2 percent allethrin dusts 
caused about the same mortality as 0.1 and 0.2 percent pyrethrins dusts, 
that is 10 to 14- percent. Even at 10 percent allethrin killed only 53.3 
percent. When tested in a greenhouse as liquefied gas aerosols containing 
1 percent of toxicant, pyrethrins were slightly superior to allethrin. 
— Bishopp ( 48 ) . 

When tested in the laboratory in the form of dusts by a modification 
of the settling tower method pyrethrins were better than allethrin against 
nymphs. — Stoddard and Dove. (177 ) . 

Brevicorvne brassicae (L.), the cabbage aphid 

Allethrin dust was inferior to pyrethrins dust. — Roark ( 14.9) . 

Macro siphoniella sanborni (Gill.), the chrysanthemum aphid 

When tested in a greenhouse as liquefied gas aerosols containing 1 
percent of toxicant pyrethrins were slightly superior to allethrin. — 
Bishopp C4£). 

Macro siphum pi si (Kltb.), the pea aphid 

Allethrin dust was 1/2 as effective as pyrethrins dust; allethrin 
spray was less effective than pyrethrins spray.— Bishopp (4.8) . 

Pyrethrin dusts were from 2 to 3.4 times more effective than allethrin 
against 2-day old nymphs at 3 dosage levels, liquid dosages of 0.012$ 
percent v/v of both materials were about equally effective. At intermediate 
and low mortality levels allethrin was less effective. — Bottger and Yering- 
ton (5Z). 

In laboratory tests allethrin and pyrethrins in the form of pyrophyllite 
dusts and aqueous emulsions (made by adding an acetone solution to water) 
compared as follows on the basis of 50-percent mortality values: 

pyrethrins - 14. x allethrin (dusts) 

pyrethrins = 3.8 x allethrin (dips) — Bottger (50) . 



Macro siphum solanifolii (Ashm.), the potato aphid 

In laboratory spraying tests in England allethrin was only l/l6 as 
toxic as pyrethrins. — Elliott .et al. (66). 

Myzus solani (Kltb.), foxglove aphid 

In greenhouse tests aerosols of allethrin and of pyrethrins were 
equally effective. — Roark (149) . 

Myzus persicae (Sulz.), the green peach aphid 

Allethrin dust was inferior to pyrethrins dust. — Roark ( 14,9 ) . 

Aphis rosarum Kltb., 

Allethrin at the rate of 0.06 pounds per 100 gallons of water killed 
100 percent of the aphids; pyrethrins at the same strength killed 97 percent. 
Dreft (used as a wetting agent at 0.06 pound per 100 gallons of water) alone 
killed 37 percent of the aphids. — Bishopp (4.8). 

Cicadellidae 

Circulifer teneilus (Baker), the beet leaf hopper 

Allethrin dust was inferior to pyrethrins dust. — Roark ( 149 ) . 

Macrosteles divisus (Uhl.), the six- spotted leaf hopper 

Emulsions and dusts of pyrethrins were more effective than those of 
allethrin. — Moore ( 134. ) . 

In greenhouse tests of aerosols, allethrin proved inferior to pyrethrins. — 
Roark (U9 ). 

Coccidae 

Phenacoccus gossypii T. & C, the Mexican mealybug 

Allethrin, 0.125 pound per 100 gallons of water plus 0.08 pound of Dreft 
killed 84 percent, pyrethrins 92 percent, and Dreft alone 14 percent. When 
tested as liquefied gas aerosols containing 1 percent of toxicant in a green- 
house pyrethrins were slightly superior to allethrin. — Bishopp (48) . 

HETER0PTERA 

Coreidae 

Anasa tristis (Deg.), the squash bug 

In the form of water emulsion sprays pyrethrins were 3 times as effective 
as allethrin and a dust containing 0.23 percent of pyrethrins killed £6 percent, 



whereas a dust containing 0.4-6 percent of allethrin killed 21 percent. — Moore ( 1 3 A ) . 

Pyrethrin dust was better than allethrin dust against nymphs and adults. 
—Stoddard and Dove (177 ). 

Lygaeidae 

Oncopeltus fasciatus (Dall.), the large milkweed bug 

When tested as dusts allethrin was 1/2 as effective as pyrethrins: 
when tested as sprays allethrin was twice as effective as pyrethrins. — Bishopp(£8) . 

Pyrethrin dusts were twice as effective as allethrin against 3rd instar 
nymphs. When tested as 0.0125-percent sprays allethrin was twice as effective 
as pyrethrins and when the dosage was reduced to 0.0055 in the allethrin it 
was 5 times more effective than pyrethrins. — Bottger and Yerington (52) . 

In laboratory tests allethrin and pyrethrins in the form of aqueous 
emulsions (made by adding an acetone solution to water) compared as follows 
on the basis of 50 percent mortality values. 

allethrin = 2.5 x pyrethrins (sprays) — Bottger (50) . 

Miridae 

Lygus oblineatus (Say), the tarnished plant bug 

In greenhouse tests allethrin spray (32 ounces of U percent solution 
per 100 gallons equivalent to 0.01-percent concentration) was ineffective; the 
control 96 hours after spraying was 25 percent. — Zia-Din ( 195 ) . 

Pentatomidae 

Murgantia histrionica (Hahn)« the harlequin bug 

When tested in the laboratory in the form of dusts by a modification of 
the settling tower method pyrethrins were better than allethrin. — Stoddard 
and Dove ( 177 ). 

AN0PLURA 

Haematopinidae 

Haematopinus eurvsternus (Nitx.), the short-nosed cattle louse 

When 0.05-percent sprays were applied to cattle infested with the short- 
nosed louse, motile forms were killed by both pyrethrins and allethrin. 
— Roark (U9). 

Pediculidae 

Pediculus humanus corporis Deg., the body louse 

Laboratory tests indicated that body lice in Korea which were highly 
resistant to DDT were about as susceptible to allethrin as normal laboratory 



colony lice at Orlando, Florida. In beaker tests (cloth impregnation) 
0.05-percent allethrin caused 100 percent mortality after 2k hours exposure; 
0.01-percent caused 62 percent mortality. In laboratory tests on residual 
effectiveness, the pyrethrin 2,4--dinitroanisole formulations appeared some- 
what more effective than similar formulation containing allethrin in place of 
2,^-dinitroanisole. Six pyrethrin and allethrin powder formulations caused 
good reductions of lice in field tests after one treatment and almost complete 
eradication of lice after three treatments. All six formulas appeared equally 
effective under the conditions in which the tests were made. Pyrethrins and 
allethrin at a concentration of 0.1 percent caused 100 percent mortality of lice 
in 2k hours. Both caused complete knockdown at a concentration of 0.05 percent, 
but the pyrethrins did not give complete mortality in 2k hours. At a concen- 
tration of 0.025 percent neither material caused complete knockdown or kill in 
2k hours. In recent tests with the non-resistant strain of lice at the Orlando, 
Florida laboratory, a concentration of 0.05 percent of either material generally 
caused complete knockdown but rather low mortalities in 2k hours. It would 
appear, therefore, that there is little difference in the susceptibility of 
normal and DDT-resistant Korean strains of body lice to allethrin and pyrethrins. 
—Eddy (64). 

C0LE0PTERA 

Anobiidae 

Lasioderma serricorne (F. ), the cigarette beetle 

A spray containing allethrin was inferior to one containing pyrethrins. 
~Roark(U9). 

Chrysomelidae 

Acalvmma vittata (F.), the striped cucumber beetle 

See under Diabrotica . — Stoddard and Dove (177 ) . 

Altica ambiens (Lee), the alder flea beetle 

Allethrin was more effective than pyrethrins both in dusts and in sprays. 
— Bishopp (k8). 

Allethrin dust was 17 percent more toxic than pyrethrins dust. Allethrin 
spray 0.05 percent v/v killed 29 percent of the test insects, whereas 
pyrethrins at 0.10 percent v/v killed none. — Bottger and Yerington (52). 

Diabrotica undecimpunctata howardi Barb., the spotted cucumber beetle 

When tested in the form of dust in the laboratory by a modification of 
the settling tower method allethrin proved inferior to pyrethrins. — Stoddard 
and Dove (177). 



Diabrotica sp. 

In cage tests of impregnated dusts a dust containing 0.23 percent of 
pyrethrins was better than one containing 0.^6 percent of allethrin. — Moore ( 13A ) . 

Lentinotarsa decemlineata (Say), the Colorado potato beetle 

When tested in the laboratory in the form of dusts by a modification of 
the settling tower method pyrethrins were better than allethrin. — Stoddard and 
Dove (177). 

Phaedon cochleariae (F.), the mustard beetle 

In laboratory spraying tests pyrethrins were 5 times as toxic as allethrin 
to adult beetles. — Elliott .et ^1. (66). 

Coccinellidae 

Epilachna varivestis Muls., the Mexican bean beetle 

When tested in the laboratory in the form of dusts by a modification of 
the settling tower method pyrethrins were better than allethrin against adults 
and larvae. — Stoddard and Dove (177) . 

Cucuj idae 

Oryzaephilus surinamensis ( Lj, the saw-toothed grain beetle 

In laboratory spraying tests on adult beetles pyrethrins were about 
2 1/2 times as toxic as allethrin. — Elliott et al. ( 66 ) . 

Curculionidae 

Listroderes costjrostr^s obliquus Klug, the vegetable weevil 

A dust containing allethrin was inferior to a pyrethrins dust. — Roark (l£9 ) . 

Sitrophilus oryza (l.j, the rice weevil 

Adult weevils were immersed for 5 minutes in 0.5-percent emulsions of 
allethrin and pyrethrins at 20° C. Allethrin caused less mortality than 
pyrethrins 24 hours after treatment, but more mortality at £8 hours and 72 
hours after treatment. — Sakai .et al. ( 153 ) . 

Dermestidae 

Attagenus pjceus (Oliv.), the black carpet beetle 

Beetle larvae were exposed to cloth impregnated with acetone solutions of 

toxicants. Allethrin at 5 mg./sq. ft. produced slightly less knockdown but 

higher mortality and a longer residual action than pyrethrins. At 15 mg./sq. 

ft. allethrin exhibited about the same knockdown, slightly lower mortality and 
longer residual effectiveness than pyrethrins. Piperonyl butoxide and n-propyl 



isome increased the knockdown of allethrin but not the mortality. — Bishopp (48.). 

Scarabaeidae 

Popillia japonica Newm., the Japanese beetle 

When tested in the laboratory in the form of dusts by a modification of 
the settling tower method pyre thr ins were superior to allethrin. — Stoddard and 
Dove (177). 

Tenebrionidae 

Tribolium confusum Duv., the confused flour beetle 

By the glass plate method residues of allethrin and pyrethrins caused 
equal mortality after 12 days contact and one synergist (sulfoxide) greatly 
increased the kill with allethrin. — Bishopp (£8) . 

Deposits of allethrin on glass plates paralyzed adult beetles less rapidly 
than did deposits of pyrethrins and the beetles recovered much more rapidly and 
completely than those that had been exposed to the pyrethrins. — Stoddard and 
Dove (177). 

Sprays containing 0.5 percent pyrethrum or allethrin are recommended by 
the Bureau of Entomology and Plant Quarantine for combating insects in empty 
grain bins, These sprays should be applied at the rate of 2 gallons per 1,000 
square feet of wall or floor surface. — U. S. Dept. Agr. (18A ) . 

LEPIDOPTERA 

Hyponomeutidae 

Plutella maculipennis (Curt.), the diamondback moth 

In labortory spraying tests in England against final instar larvae 
allethrin was nearly twice as effective as pyrethins. — Elliott et .&1 . (66). 

During the spring of 1950 natural pyrethrum powder and allethrin, were 
compared in the laboratory and in field plots in South Carolina. In general, 
allethrin dusts proved less toxic than those of similar pyrethrin content. 
Higher dosages of allethrin, however, showed considerable promise. In a small 
field test, a 1-percent allethrin dust was about as effective as a 0.3~percent 
allethrin dust against a mixed infestation of the cabbage looper, the imported 
cabbageworm, and the diamondback moth. — Reid and Cuthbert (142) • 

Papilionidae 

Papilio polvxenes F. 

Emulsions and dusts of pyrethrins were more effective than those of 
allethrin. — Moore ( 13£ ). 



.K.'Stf-* 



Phalaenidae 

Alabama argillacea (Hbn.)» the cotton leaf worm 

When tested against the cotton leaf worm as 1- and 2-percent dusts at 
10 pounds per acre allethrin showed 5 to 15 percent kill while pyrethrins 
at 0.5 percent gave a 25 percent kill. — Bishopp (48) . 

Pseudaletia unjpuncta (Haw.), the armyworm 

When tested as dusts allethrin was more effective than pyrethrins, but 
in the form of sprays there was no difference. — Bishopp (48). 

At low and intermediate levels allethrin dust was 4.0 and 10 percent 
respectively more toxic than pyrethrins; at high levels pyrethrins were 31 
percent more effective than allethrin. As sprays allethrin and pyrethrins 
exhibited similar toxicity. — Bottger and Yerington (52) . 

In laboratory tests allethrin and pyrethrins in the form of pyrophyllite 
dusts and aqueous emulsions (made by adding an acetone solution to water) 
compared as follows on the basis of 50-percent mortality values: 

pyrethrins = 2.8 x allethrin (dusts) 

pyrethrins =10.9 x allethrin (sprays) — Bottger ( 50 ) 

Heliothi.s armjgera (Hbn.) the corn earworm 

When tested in the laboratory in the form of dusts by a modification of 
the settling tower method pyrethrins were better than allethrin. — Stoddard and 
Dove (177). 

In injection tests in California in which the toxicants were dissolved 
in USP mineral oil, Saybolt viscosity 145 to 155 seconds, 0.4 percent of 
allethrin plus 2 percent of MGK 264 was inferior to 0.1 percent of pyrethrins 
plus 2 percent of the same synergist. However, both allethrin and pyrethrum 
mixtures gave poor control in these tests. — Anderson ejt al. (4.5) . 

Trichoplusia ni (Hbn.), the cabbage looper 

Emulsions and dusts of pyrethrins were more effective than those of 
allethrin. — Moore (134 ) . 

See also under Plutella maculipennis . — Reid and Cuthbert ( 14 , 7 ) . 

Phycitidae 

Ephestia eleutella (Hbn.), the tobacco moth 

An oil spray containing 0.2 percent of allethrin killed as many moths as 
a pyrethrins- oil spray. — Roark ( 149 ) . 



Pieridae 

Pieris rapae (L.), the imported cabbage worm 

Emulsions and dusts of pyrethrins were more effective than those of 
allethrin. — Moore ( 13£ ) . 

See also under Plutella maculipennis . — Reid and Cuthbert (147 ). 

Pyraustidae 
Diaphania nitidalis (Stoll), the pickle worm 

Allethrin dust was inferior to pyrethrins dust. — Roark ( 1A9 ) . 

Phlyctaenia rubigalis (Guen.)» the celery leaf tier 

Allethrin was 1/4 as effective as pyrethrins when tested as dusts, but 
was 10 times as effective when tested as sprays. — Bishopp (48) . 

Against 3rd instar celery leaf tier larvae pyrethrins sprays were 27.6 
times as toxic as allethrin sprays and when tested as dusts pyrethrins were 
13 times as toxic as allethrin. — Bottger and Mayer (51) . 

Pyrethrins dust was about 4 1/2 times as effective as allethrin dust 
against 3rd instar larvae, but allethrin was roughly 10 times more effective 
than pyrethrins when tested as sprays. — Bottger and Yerington (52) . 

Pyrausta nubilalis (Hbn.), the European corn borer 

Allethrin at 0.5 ounce for 100 gallons of water caused 100 percent 
mortality of newly hatched larvae. At l/8 ounce the mortality was 33.7 percent. 
Pyrethrins in the form of powdered pyrethrum flowers at 1/100 pound per 100 
gallons water gave a kill of 100 percent and at 1/2 this dosage the kill was 
23 percent. Pyrethrins were thus about 3 times as toxic to young corn borers 
as allethrin. In these tests the toxicity of allethrin was increased as much 
as 8 fold with the addition of various synergists. — Bishopp (48). 

Emulsions and dusts of pyrethrins were more effective than those of allethrin 
against 3rd and 5th instar larvae. — Moore (134 ) . 

Sphingidae 

Protoparce sexta (Johan.), the tobacco hornworm 

Allethrin dust was inferior to pyrethrins dust. — Roark (149 ). 



HYMEN OPTERA 

Formic id ae 

Monomorium minimum Buckl., the little black ant 

Ants were exposed for 30 minutes on pads treated with insecticides. 
When the pads were aged 8 days after treatment pyrethrins caused 1? percent 
mortality as compared to 31 percent for allethrin. The addition of piperonyl 
butoxide or n-propyl icome did not materially improve the effectiveness of 
either product. When the pads were aged only one day the mortality at the 48 
hour reading was increased to some extent by the addition of these synergists. 
— Bishopp (48) . 

DIPT ERA 

Culicidae 

Aedes aegypti (L.), the yellow-fever mosquito 

Tests with 0.1 and 0.2-percent solutions of allethrin and pyrethrins 
alone applied as space sprays showed allethrin to be slightly less effective. 
The addition of 2 percent of piperonyl butoxide materially stepped up the 
action of allethrin but did not enhance that of the pyrethrins. — Bishopp (48) . 

Against 3rd instar larvae allethrin was approximately 1/3 as toxic as 
pyrethrins at the LD-50 level; 0.19 ppm as compared to 0.059 ppm. The addition 
of sulfoxide (5 parts) or piperonyl butoxide (5 parts) to one part of allethrin 
did not enhance its toxicity whereas these synergists did slightly raise the 
toxicity of pyrethrins. — Granett et al. (86) . 

Allethrin in sprays (1 mg./ml.) at a dosage of 55.56 ml./lOOO cu. ft. 
killed 100 percent of the males and 99 percent of the females in 1 day; 
pyrethrins (0.2 mg./ml.) killed 82 percent of the males and 62 percent of the 
females. — Fales e_t al. (70) . 

Aedes spp., flood-water mosquitoes 

Allethrin and pyrethrins were applied to cages at the rate of 0.5 mg. 
per sq. ft. and 24 hours later mosquitoes were introduced and exposed for 2 
minutes. Pyrethrins gave a mortality of 74 percent and two samples of allethrin 
58 and LM, percent. V.'hen piperonyl butoxide was added to each product all the 
mosquitoes exposed 2 hours in cages treated with pyrethrins were killed; when 
exposed in cages treated with allethrin the kills were 63 and 45 percent. 
— Bi shopp (A&.) . 

Anopheles ouaxlrimaculatus Say, the common malaria mosquito 

Allethrin spray, 1 mg./ml. at a dosage of 9.26 ml./lOOO cu. ft. killed 
65 percent of the males and 16 percent of the females in 1 day; pyrethrins at 
0.2 mg./ml. at the same dosage killed 73 percent of the males and 43 percent 
of the females. At a dosage of 55.56 ml./lOOO cu. ft. allethrin killed 100 



percent of the males and 99 percent of the females; pyrethrins killed (at a 
dosage of 9.26 ml./lOOO cu. ft.) 67 percent of the maQ.es and 38 percent of 
the females. — Pales .et al. (70). 

Culex pipiens var. pallens Coq. 

In Japan Nagasawa et al. (13^ ) reported that mosquito incense containing 
allethrin was about 1.5 times as effective as a similar pyrethrin incense to 
adults. When applied in oil solution to the pupae allethrin was about 0.06 
times as toxic as pyrethrins at LD-99.27. — Nagasawa et al. (137 ) . 

Fales et al. (69) reported that in Peet-Grady tests with allethrin on 
free-flying laboratory reared Aedes aegypti . Anopheles cuadrimaculatus and 
Culex pipiens the Aedes were the least resistant and the Culex were the most 
resistant. When the mortality figures for Aedes females were plotted, it was 
found that the LC-50 of allethrin was eight times that of the pyrethrins. 
With Anopheles twice and with Culex approximately five and one-half times the 
amount of allethrin was required. Against male Aedes t the amount allethrin 
required was again eight times that of pyrethrins. With Anopheles the materials 
gave nearly equal performances. With Cu lex the lowest concentration of allethrin 
(3.2 mg./ml.) gave approximately the same results as the highest concentration 
of pyrethrins (1.6 mg./ml.). 

Drosophilidae 

Drosophila melanogaster Mg., the pomace fly 

Sakai £i al. (1^2 ) tested the action of insecticides on the "vestigial 
form" of the pomace fly by immersing the insects into emulsions of the insecti- 
cides for ? minutes at 20° C. and determining the mortality after 30 minutes. 
In experiments on insecticide alone, pyrethrins were markedly more toxic than 
the other insecticides, but allethrin was more toxic than the other synthetic 
insecticides as regards MLD values. On the basis of the MLD, the toxicities 
of each contact insecticide were expressed in order of effectiveness as follows, 

I) pyrethrins, 2) allethrin, 3) rotenone, 1+) gamma BHC, 5) TEPP, 6) pp»DDT, 

7) op'DDT, 8) parathion, 9) 0,0-diethyl-O-para-nitrophenylphosphate, 10) dieldrin, 

II) nicotine, 12) aldrin and 13) toxaphene. Although chlordane was tested in 
the present investigation, it was not toxic against the pomace fly. Synergism 
was exhibited by a mixture of allethrin and BHC and antagonism by allethrin 
plus rotenone, and allethrin plus pyrethrins. 

Hippo bo scidae 
Melophagus ovinus (L.), the sheep tick 

Sprays of pyrethrins were superior to those of allethrin. — Roark ( 14.9 ) . 

Mycetophili dae 
Bradvsia fenestralis (Zett.) 
Megaselia agarici (Lint.) 



Adults of both species of mushrooir. flies appeared more susceptible to 
pyrethrins dust than to allethrin dust. — Roark (149) ♦ 

t^fuscidae 

Musca domestica L., the house fly 

When applied as space sprays against house flies natural pyrethrins 
were slightly more effective than allethrin at 0.1 percent, but at 0.2 percent 
the reverse was true, '//hen piperonyl butoxide was added to allethrin in a 
5:1 ratio there was a 34 percent increase in toxicity as compared with a 54 
percent increase when the pyrethrins were used. Cages were dipped in acetone 
solution containing 0.1 percent of various toxicants and after 24 hours flies 
were introduced. Allethrin killed 74 percent and pyrethrins 47 percent of the 
flies. When 1 percent of piperonyl butoxide was added the toxicity of the 
pyrethrins was increased to 92 percent whereas the toxicity of allethrin remained 
unaffected. — Bishopp (48) . 

When tested by the Peet-Grady method allethrin was less effective than 
pyrethrins at low concentrations (below approximately 125 mg./lOO ml.) but 
was more effective at concentrations above this. To give 50 percent kill of 
the house flies 145 mg./lOO ml. of allethrin were required as compared to 
165 mg./lOO ml. of pyrethrins. An allethrin residue on a glass plate was more 
effective in knockdown and kill than an equal residue of pyrethrins. A 1 percent 
allethrin aerosol was almost, but not quite, the equivalent of a 1 percent 
pyrethrin aerosol. — Nash ( 139 ) . 

Blackith ( 49 ) in 1951 stated that in his experience and in that of Elliott 
.et .al . , allethrin gives parallel regression lines with the natural extracts. 

In tests with sprays containing 1 mg. of toxicant per milliliter of 
deodorized kerosene allethrin and pyrethrins gave the same kill (25 percent in 
1 day) and essentially the same knockdown in 10 minutes (87 and 84 percent, 
respectively). In tests with aerosols (89 percent of Freon 12, 6 percent of 
methylene chloride, 4 percent of deodorized kerosene and 1 percent of toxicant) 
applied at a dosage of 4.63 grams per 1000 cu. ft. allethrin and pyrethrins 
gave the same kill (32 percent in 1 day) and almost the same knockdown in 10 
minutes (69 and 73 percent, respectively). — Fales et al. (70). 

When tested in aerosols allethrin is equal to pyrethrins in knockdown and 
kill. The addition of 2 percent of DDT enhances the kill of both materials. 
The synergistic effect of piperonyl butoxide is considerably less with allethrin 
than with pyrethrins. — Moore (134 ) . 

When sprayed in 0.1-percent Deobase solution on adult flies allethrin was 
superior to pyrethrins in both 10-minute knockdown and 24-hour kill. When exposed 
to ultraviolet light for 5 hours (equivalent to 5 days exposure to mid-day sun) 
and to heat (110°F. for 24 hours and to 120°F. for an additional 48 hours) allethrin 
proved more stable than pyrethrins. These tests were made on mosquito larvae and 
house flies. An allethrin residue of 144 mg. per sq. ft. persisted for several 
months against house flies and when a synergist (piperonyl butoxide or sulfoxide) 
was added the amount of residue could be reduced to 28 mg. per sc. ft. — Granett 
et £X • (3k) • 



In tests made by the turntable method allethrin was about 3 times as 
toxic as the pyrethrins. — Gersdorff (77) ♦ 

In England Crombie e_t al. (61) quote Parkin and Green of the Pest 
Infestation Laboratory as reporting that when allethrin and pyrethrins 
were tested over the concentration range 0.05-0. A percent w/v in odorless 
distillate by a modified Peet-Grady method "There was no difference in 
toxicity between the two sets of corresponding solutions either in knock- 
down in 10 minutes or in kill in 24. hours." 

March and Ketcalf (122) in 1950 reported that resistant and nonresistant 
houseflies showed approximately the same level of susceptibility to pyrethrins 
and allethrin. In these tests the insecticides in acetone solution were applied 
to flies with a micro- syringe. The 24-hour LD-50's in micrograms per female 
fly were: 

Laboratory strain Bellflower strain Pollard strain 

Pyrethrins 1.0 0.94 1.6 

Allethrin 0.43 0.97 0.5 

On the basis of LC-50's the Bellflower strain of flies was more than 300 
times as resistant to DDT as the non-resistant laboratory strain and the 
Pollard strain was even more resistant. On the basis of LD-95's the Bellflower 
strain was more than 1500 times as resistant to DDT as the laboratory strain. 
The authors conclude that the use of space sprays or aerosols containing 
pyrethrins or the equivalent represents the only satisfactory means for the 
chemical control of flies resistant to both DDT and BKC. 

Houseflies from a dairy near Orlando, Florida that were " times as 
resistant as regular flies to DDT exhibited no increased resistance to pyrethrins 
plus piperonyl butoxide and allethrin plus piperonyl butoxide. — Knipling ( 110 ). 

Cuarterman ( 129) of the U. S. Public Health Service at the 19th Annual 
Convention of the National Pest Control Association held in Boston October 30, 
1951 stated that for the control of resistant flies pyrethrum with synergists 
can be used successfully. Allethrin is a promising substitute for pyrethrum 
in some cases but not in others. 

Houseflies which were resistant to DDT in 1949 acquired increased 
resistance to five additional chlorinated hydrocarbons in 1950, but little 
or none to allethrin and pyrethrins. — Gilbert et al. (84). 

Against resistant flies in Florida allethrin and pyrethrins plus piperonyl 
butoxide were moderately effective early in 1950, but by the end of the season 
none of them provided satisfactory control. — Wilson et §1 . ( 194 ) . 

Siphona irritans (L.), the horn fly 

A dust containing 0.5 percent of allethrin applied at the rate of 2.3 
to 2.5 ounces per animal caused 53 percent reduction in the number of horn flies 



on cattle in tests at Oswego, New York in 1950. A spray of Fvrenone 1-5 
caused the greatest reduction - 96 percent. — Goodwin et al. (85) . 

Stomoxys calcitrans (L.), the stable fly 

To tast the residual effectiveness of allethrin and pyrethrins screen- 
wire cages v/ere dipped into 0.1-percent solutions of these toxicants alone 
and with the addition of 1 percent of piperonyl butoxide. Stable flies were 
introduced one day later and exposed for 24 hours. In two tests pyrethrins 
gave a 100 percent knockdown and kill with and without the synergist whereas 
allethrin alone gave 60 and 92 percent knockdowns and 4.0 and 85 percent kills 
and the mixture 87 and 82 percent knockdowns and 72 and 70 percent kills. 
Additional tests with stable flies introduced 4 days after treatment indicated 
that pyrethrins were much more effective than allethrin from a residual stand- 
point and the addition of piperonyl butoxide did not enhance the effectiveness 
of allethrin. — Bishopp (48) . 

Tabanidae 

Chrysops discalis Will., the deer fly 

Tabanus sonomensis O.S.) 

) horse flies 
T. Eunctifer O.S. ) 

A concentration of 1 mg. per square foot or greater was necessary to 
obtain knockdown of the deerfly in less than two hours with either natural 
pyrethrins or allethrin when used alone. Natural pyrethrins plus synergists 
usually produced superior results to those obtained with allethrin and the 
same synergist. At 0.5 mg. per square foot of pyrethrins and 5 mg. per square 
foot of synergist, piperonyl butoxide was the most effective synergist, resulting 
in complete knockdown in an average of 3 minutes with either natural pyrethrins 
or allethrin and a 100 percent mortality in 8 hours after an exposure of 1 1/2 
minutes to the treated surfaces. Lower dosages, however, provided greatly 
reduced effectiveness particularly in relation to the synthetic product. — Hoffman 
and Lindquist ( 103 ) . 

Tabanus quinquevittatus Veidemann 

A dust containing 0.5 percent of allethrin applied at the rate of 2.3 to 
2.5 ounces per animal caused 4-5 percent reduction in the number of horse flj 3s 
on cattle in tests at Oswego, New York in 1950. A spray of Pyrenone 1-10 
caused the greatest reduction -93 percent. — Goodwin et al. (85) . 

ACAFJNA 

Argasidae 

Otobius megnini (Duges), the ear tick 

Allethrin was less effective than pyrethrins in tests against spinose 
ear ticks and winter ticks in which the ticks were dipped in acetone solution 
of the insecticides. — Roark ( 149 ) . 



Ixodidae 

Dermacentor albipictus (Pack.), the winter tick 

See lander spinose ear tick. 

Tetranychidae 

Faratetranvchus citri (McG.), the citrus red mite 

Allethrin and pyrethrins as 2-percent dusts were ineffective; as sprays 
11-percent v/v dosages of both materials gave 100 percent mortality. — Bottger 
and Yerington ( 5 , 2 ) . 

Tetranychus bimaculatus Harvey, the two spotted spider mite 

Allethrin at 0.125 pounds per 100 gallons caused 56 percent dead and 
moribund; twice this concentration raised the percentage to 72. The corres- 
ponding figures for pyrethrins were 8 and 89 percent. These toxicants were 
dispersed in water with Dreft. When tested in a greenhouse as liquefied gas 
aerosols containing 1 percent of toxicant pyrethrins were slightly superior to 
allethrin. A spray of allethrin was about equal to one of pyrethrins, but 
allethrin dust was 1 1/2 times as effective as pyrethrins dust. — Bishopp (£8) . 

Allethrin dust was about 73 percent more effective than pyrethrins dust. 
When tested as sprays of 0.1 percent concentration allethrin was slightly 
superior to pyrethrins. — Bottger and Yerington (52) . 

Tetranvchus sp., red spider 

Against the red spider on cotton a dust containing 0.1 percent of the 
toxicant in Attaclay was applied at the rate of 10 pounds per acre. The kill 
after 60 hours was 19.7 percent for allethrin and 4-. 6 percent for pyrethrins. 
The addition of piperonyl butoxide failed to increase the kill. — Bishopp (£8) . 



LITERATURE CITED 

(1) Anonymous 

194.9. An active principle of pyrethrum synthesized. Chem. and Engin. 
News 27: 930. March 28. 

(2) 

1949. New pyrethrum-like synthetic insecticide. Pests 17(4): 32. 
April. 

(3) 

1949. Chemical warfare USDA. USDA 8(9): 1. April 25. 

(4) 

1949. [Synthetic pyrethrum. J Editorial. Agr. Chem. 4(4): 23-24. 

( 5) _— 

1949. Insecticide synthesized. Chem. and Engin. News 27: 1942- 
1943. July 4. 

(6) 

1949. [Synthesizing pyrethrum.] Editorial. Agr. Chem. 4(7): 19-20. 
July. 

(7) 

1949. Penick synthesizes pyrethrum. Agr. Chem. 4(7): 63. July. 

(8) 

1949. Penick now making synthetic pyrethrins. Oil, Paint and Drug 
Rptr. 156(1): 5. July 4. 

( 9 ) 

1949. USI producing cinerin homolog. Soap and Sanit. Chem. 25(9): 
155. Sept. 

(10) 

1949. fAllyl homolog of cinerin I.] Soap and Sanit. Chem. 25(9): 
172. Sept. 

(11) 

1949. fAllyl homolog of cinerin I.] Chem. and Engin. News 27: 
2669. Sept. 19. 

(12) 

1949. Flowers not necessary. Chem. and Engin. News 27: 2754. Sept. 26. 

(13) 

1949. Synthetic pyrethrum output in large lots approaching. Oil, 
Paint, and Drug Rptr. 156(13): 5. Sept. 26. 



( 14 ) Anonymous 

1949. fSynthetics related to pyrethrins.] Che/n. and Zngin. News 

27:2923. Oct. 10 

(15) 

194-9. Active pyrethrum factor to be produced by U.S.I. Chem. and 
Engin. News 27: 2989. Oct. 17. 

(16) 

1950. U.S.I, acquires foreign rights to * synthetic pyrethrum 1 patents. 

Chem. and Engin. News 28: 941-942. March 20. 

(17) 

1950. Commercial production of synthetic pyrethrin. Chem. and 
Engin. News 28: 1138. April 3. 

(18) 

1950. Kenya kaput? Chem. Ind. 66: 506-507. April. 

(19) 

1950. Synthetic pyrethrin. Chem. and Engin. News 28: 1234. 
April 10. 

(20) 

1950. Aerosol dominates discussions of specialty manufacturers. 
Chem. and Engin. News 28: 2170-2171. June 26. 

(21) 

1950. Pyrethrum acreage in Kenya reduced sharply in 1949. Oil, 
Paint and Drug Rptr. 158(5): 59. July 31. 

(22) 

1950. Green light. Chem. and Engin. News 28: 3857-3858. Nov. 6. 

(23) 

1950. Army-Navy needs. Chem. and Engin. News 28: 4442. Dec. 18. 

(24) 

1951. Army okays allethrin, MGK expands. Chem. and Engin. News 

29: 3. Jan. 1. 

(25) 

1951. Prop for allethrin. Chem. Indus. Week 68(2): 11-12. Jan. 27. 

(26) 

1951. MGK allethrin expansion. Soap and Sanit. Chem. 27(2): 155. Feb. 

(27) 

1951. Allethrin, a new insecticide. The Capital Chemist 1(3): 70-71. 
March. 

(28) 

1951. Pyrethrum outlook and where increased output of allethrin will 

fit into the picture. Soap and Sanit. Chem. 27(3): 114-115. March. 



(29) Anonymous 

1951. Research to application. USDA Employee News Bui. 10(7): 5. 
March 28. 

(30) 

1951. USI plans to construct allethrin unit in Baltimore. Oil, Paint 
and Drug Rptr. 159(17): 5. April 23. Also in Chem. and 
Engin. News 29: 1740. April 30. 

(3D 

1951. Bugs beware. Chem. and Engin. News 29: 1800. May 7. 

(32) 

1951. Allethrin attains rank as commercial chemical. Chem. and Engin. 
News 29: 1946. May H. 

(33) 

1951. U.S.I, to build new plant to produce allethrin. Chem. and 
Engin. News 29: 2477-2478. June 18. 

(34) 

1951. Sprouting allethrin. Chem. Week 69(6): 30-31. Aug. 11. 

(35) 

1951. Seventy-five years of chemical progress - A story in pictures. 
[Synthesis of an active principle of pyrethrum.l Chem. and 
Engin. News 29: 3340. Aug. 13. 

(36) 

1951. Carbide to build large allethrin plant. Chem. and Fngin. News 
29: 3539. Aug. 27. 

(37) 

1951. Pesticides on Notice 1. Soap and Sanit. Chem. 27(12): 169. Dec. 

(38) 

1952. McLaughlin-Gormley-King celebrates fiftieth year. Oil, Paint 

and Drug Rptr. 161(19): 5, 49. May 12. 

(39) 

1952. Allethrin follow-up. Chem. Week 70(22): 30. May 31. 

(40) 

1952. Coals to Newcastle. Chem. and Engin. News 30: 252A. June 16. 

(41) 

1952. Doubled, redoubled and doubled again. Chem. Week 70(26): 64-65. 
July 5. 

(42) 

1952. McLaughlin Gormley King reduces prices on allethrin. Oil, Paint 
and Drug Rptr. 162(4): 5. July 28. 



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1951. Handbook of Agricultural Pest Control. Industry Publications, 
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1950. Preliminary report on allethrin. Agr. Chem. 5(8): 22, 25, 

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1951. Some current problems of pyrethrum assay. Pyrethrum Post 2(3): 

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1952. Ground equipment and insecticides for mosquito control. Amer. 

Mosquito Control Assoc. •Bui. 2, 116 pp. March. 



(112) LaForge, F. B., Gersdorff, W. A., Green, N., and Sohechter, M. S. 

1952. Allethrin-type esters of cyclopropanecarboxylic acids and their 

relative toxicities to house flies. Jour. Org. Chem. 17: 381-389. 

(113) Green, N., and Schechter, M. S. 

1952. Dimerized cyclopentadienones from esters of allethrolone. 
Amer. Chem. Soc. Jour, fin press.] 

(1H) Langford, G. S., editor 

1951. Entoma - A directory of insect and plant pest control. 9th Ed. 
Amer. Assoc. Econ. Entomologists, College Park, Md. 1J& pp. 

(115) Lehman, A. J. 

1951. Chemicals in foods. A report to the Association of Food and Drug 
Officials on current developments. II. Pesticides. Assoc. 
Food and Drug Officials U. S. Quart. Bui. 15: 122-123. 

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1950. Some toxicological reasons why certain chemicals may or may not 

be permitted as food additives. Assoc. Food and Drug Officials 
U. S. Quart. Bui. H(3): 82-98. 

(117) McLaughlin Gormley King Company 

1951. There is no shortage of MGK allethrin! [Advertisement.] Chem. 

and Engin. News 29: 5189. Dec. 3. 



1951. Use MGK pyrethrum with MGK allethrin. [Advertisement.] Soap 
and Sanit. Chem. 27(12): 133. Dec. 



(119) 

1952. A report to the industry on allethrin. Soap and Sanit. Chem. 
28(6): 105-108. June. [Advertisement.] 

(120) McNamee, R. W. 

1950. First commercial synthesis of allyl cinerin. Carbide and Carbon 
Chemicals Division, Union Carbide and Carbon Corp., 30 E. 4.2nd 
Street, New York 17, N. Y. News Release, 3 pp.* 1 fig. 
March 20. [Processed.] 



1950. General nature of allethrin. Chem. Spec. Mfrs. Assoc. Proc. 36: 
57. [Soap and Sanit. Chem. Special Issue.] Also in Soap and 
Sanit. Chem. 26(8): 106. 



(122) March, R. B., and Metcalf, R. L. 

1950. Studies in California of insecticide-resistant flies. Chem. 
Spec. Mfrs. Assoc e Proc. 36: 80-83. [Soap and Sanit. Chem. 
Special Issue.] 



(123) Matsui, M., Kitamura, S., Kato, T., and Sugihara, T. 

1950. Synthesis of cyclopentolones of the cinerolone type. Jour. 
Chem. Soc. Japan Pure Chem. Sect. 71: 235-236. 

(124) LaForge, F. B., Green, N., and Schechter, M. S. 

1952. Furethrin. Amer. Chem. Soc. Jour. 74: 2181-2182. 

(125) Maughan, F. B., Mizell, F. M. , and Nichols, J. P. 

1950. Further studies on aerosol formulations with lethane and other 

toxicants. Chem. Spec. Mfrs. Assoc. Proc. 37: 96-98. 
[Soap and Sanit. Chem. 27(2): 125, 127. 131. 1951. 

(126) Metal Hydrides Inc. 

1951. For bugs: a lethal daisy chain that owes its knockout punch to 

NaH. [Advertisement.] Chem. and Engin. News 29: 809. Feb. 26. 

(127) Metcalf, C. L., Flint, W. P., and Metcalf, R. L. 

1951. Destructive and useful insects - their habits and control. 
3rd Ed., McGraw-Hill Book Co., New York, 1071 pp. 

(128) Miller, A. R. 

1950. Eradication of vermin - Use of fumigants, sprays, powders and 
baits. U. S. Dept. Agr., Bur. Animal Indus., Meat Inspection 
Division Memorandum No. 52, Supplement 3, Sept. 12. 



(129) 



1951. Eradication of vermin - Use of fumigants, sprays, powders and 
baits. U. S. Dept. Agr., Bur. Animal Indus., Meat Inspection 
Division Memorandum No. 52, Supplement 4, Dec. 19. 



(130) Montrose Chemical Company 

194.9. Synthetic pyrethrins. (Allyl homolog of Cinerin I.) [ Adver- 
tisement.] Oil, Paint and Drug Rptr. 155(25): 17. June 20. 

(131) Moore, J. B. 

1950. Allethrin - standardization, analysis, storage. Chem. Spec. 

Mfrs. Assoc. Proc. 36: 58-59. [Soap and Sanit. Chem. Special 
Issue.] Also in Soap and Sanit. Chem. 26(8): 107-108. 

(132) 

1950. Synergist "264". Chem. Spec. Mfrs. Assoc. Proc. 36: 72. 
[Soap and Sanit. Chem. Special Issue.] 

(133) 

1950. The place of allethrin in the aerosol program. Chem. Spec. Mfrs. 
Assoc. Proc. 37: 89-91. [Soap and Sanit. Chem. Special Issue.] 



(134) 



1950. Relative toxicity to insects of natural pyrethrins and synthetic 
allyl analog of cinerin I. Jour. Econ. Ent. 43: 207-213. 



(135) Morrow, M. G. 

1952. Plants that kill insects. Sci. News Letter 61(21): 330-332. 

(136) Nagasawa, S., Inoue, Y., and Shibata, S. 

1951. Comparison of the toxicity of allethrin and ethythrin to pupae 
of the common house mosquito, and the joint action of these 
two toxicants. Botyu-Kagaku 16: 169-176. 

(137) Inoue, Y., and Shibata, S. 

1951. Comparison of the toxicity of pyrethrins and allethrin to 

pupae of the common house mosquito ( Culex pipiens var. pallens 
Coquillett ) . Studies on the biological assay of insecticides. 
XV. Botyu-Kagaku 16: 166-169. 

(138) Katsuda, Y., Okamota, A., and Ohno, M. 

1951. On the knock-down effect of so-called pyrethrins and allethrin 
coating mosquitocide incense to adults of the common house 
mosquito ( Culex pipiens var. pallens Coquillett ). Studies 
on the biological assay of insecticides. XVII. Botyu- 
Kagaku 16: 176-182. 

(139) Nash, K. B. 

1950. Biological tests of allethrin without synergists. Chem. Spec. 

Mfrs. Assoc. Proc. 36: 61-62. [Soap and Sanit. Chem. Special 
Issue.] Also in Soap and Sanit. Chem. 29(9): 127. 

(HO) 

1951. Insecticide Scientific Committee Report of Sub-Committee on 

Allethrin Cooperative Peet-Grady Tests. Chem. Specialties 
Mfrs. Assoc. Proc. 38: 79. 

(141) National Production Authority 

1952. Insecticide raw materials, except pyrethrum, seen in good supply. 

Oil, Paint and Drug Rptr. 161(5): 5, 45. Feb. 4. 

(142) Nelson, R. H., Fales, J. H., and Bodenstein, 0. F. 

1952. Tests with alternate synergists in armed services space spray. 
Interim Report No. C 79. June 4> 1952. 3 pp. 

(U3) Noble, H. 

1950. Allethrin for 1951. S. B. Penick and Co., Letter dated Dec. 
14. 1 page. 

(144) Penick, S. B. and Co. 

1949. Pyresyn (synthetic pyrethrum). Soap and Sanit. Chem. 25(10): 
128, and (11): 95. Oct. and Nov. Also in Agr. Chem. 4(10): 
60, and (11): 20. Oct. and Nov. 

(145) Piquett, P. G. 

1949. The effect of four commonly used synergists on a synthetic 
pyrethroid. Jour. Econ. Ent. 42: 84I-842. 



(146) Quarterman, K. D. 

1951. [Fly control.] Paper presented at 19th Ann. Convention Natl. 

Pest Control Assoc. Boston, Oct. 30. 

(147) Reid, W. J., Jr., and Cuthbert, F. P., Jr. 

1952. New insecticides tested against vegetable insect pests. S. C. 

Agr. Expt. Sta. Ann. Rpt. 63 (1951): 129-132. 

(148) Resnick, S. L., and Crowell, R. L. 

1951. Comparative evaluation of certain high pressure insecticidal 
aerosols against Musca domestics. Jour. Natl. Malaria Soc. 
10: 248-256. 

(U9) Roark, R. C. 

1951. Value of allethrin in insect control Chem. Spec. Mfrs. Assoc. 
Proc. 38: 89-91. 

(150) Rohwer, S. A. 

1950. Allethrin, a coined name for the insecticidal chemical dl-2- 
aHyl-4-hydroxy-3-methyl-2-cyclopenten-l-one esterified with 
a mixture of cis and trans dl- chrysanthemum monocarboxylic 
acid. Interdept. Com. Pest Control, U. S. Bur. Ent. and Plant 
Ouar., 2 pp., May 15. [Processed.] 

(151) 

1950. Allethrin accepted for use in gas-propelled aerosols. U. S. 

Bur. Ent. and Plant Quar., 1 p. Oct. 26. [Processed.] 

(152) Sakai, S., Sato, M., and Kozima, K. 

1951. Insect toxicological studies on the joint toxic action of 

insecticides. II. On the joint toxic action between contact 
insecticides. Botyu-Kagaku 16: 130-140. 

(153) ~ — ~ Sato, M. , and Kozima, K. 

1951. A comparison of the toxicity of several contact insecticides 
against the rice weevil, Sitophilus oryzae . Botyu-Kagaku 
16: U6-153. 

(154) Schechter, M. S., Green, N., and LaForge, F. B. 

1949. The synthesis of cyclopentenolones of the type of cinerolone. 
Amer. Chem. Soc. Tour. 71: 1517. 

(155) Green, N., and LaForge, F. B. 

1949. Constituents of pyrethrum flowers. XXIII. Cinerolone and the 
synthesis of related cyclopentenolones. Amer. Chem. Soc. 
Jour. 71: 3165-3173. 

(156) Green, N., and LaForge, F. B. 

1949. Synthesis of insecticidal esters of pyrethrin type. Agr. Chem. 
4(6): 57, 89. 



(157) Schechter, M. S., Green, N., and LaForge, F. B. 

1950. Constituents of pyrethrum flowers. XXIV. Synthetic dl-cis- 

cinerolone and other cyclopentenolones. Abstracts of papers 
118th Meeting Amer. Chem. Soc, Chicago, 111, p. 34 N. 
Amer. Chem. Soc. Jour, [in press.] 

and LaForge, F. B. 

1951. Hydroxydiketones. U. S. Patent 2,574,500. Nov. 13. 

and LaForge, F. B. 

1952. Cyclopentenolone esters of cyclopropane carboxylic acids. U.S. 
Patent 2,603,652. July 15. 



LaForge, F. B., Zimmerli, A., and Thomas, J. M. 

1951. Crystalline allethrin isomer. Amer. Chem. Soc. Jour. 73: 
3541-3542. 

Schopf, C. 

1950. Condensation of methylglyoxal with beta-oxo acids. Amer. Chem. 
Soc. Jour. 72: 2816-2817. 

Schreiber, A. A. 

1950. Synergist "264". Pest Control 18(10): 24. 

Schroeder, H. 0., and Berlin, F. D. 

1950. Allethrin in aerosols. Chem. Spec. Mfrs. Assoc. Proc. 36: 33, 

35-36. fSoap and Sanit. Chem. Special Issue.] 

Seil, Putt and Rusby, Inc. 

1951. Organic insecticides. [Advertisement.] Soap and Sanit. Chem. 

27(12): 178. 

Shepard, H. H. 

1951. The chemistry and action of insecticides. First Ed., 504 pp. 

McGraw-Hill Book Co., New York. 

Smith, H. A. 

1952. Pyrethrum at the crossroads. Soap and Sanit. Chem. 28(6): 

155, 157, 189. 

Soap and Sanitary Chemicals 

1950. Cinerin (Synthetic pyrethrum, so-called). 1950 Blue Book and 

Catalog Edition of Soap and Sanitary Chemicals, 23rd Ed., p. 13. 

1951. Allethrin. 1951 Blue Book and Catalog Edition, 24th Ed., p. 13. 

Stage, H. H. 

1951. Research on mosquitoes by the Bureau of Entomology and Plant 
Quarantine during 1950. Mosquito News 11(2): 84-89. 

Starr, D. F. 

1950. Sulfox-cide. Chem. Spec. Mfrs. Assoc. Proc. 36: 70-71. (Soap 
and Sanit. Chem. Special Issue.] 



- 56 - 

(171) Starr, D. F. 

1950. Recent advances on the allethrin- synergist combination. Chem. 
Spec. Mfrs. Assoc. Proc. 37: 82-83. fSoap and Sanit. Chem. 
Special Issue. ] 

(172) Ferguson, P., and Salmon, T. N. 

1950. Toxicity of a synthetic pyrethrin. Soap and Sanit. Chem. 
26(3): 139, LU, 143. 

(173) Ferguson, P., and Salmon, T. N. 

1950. Toxicity of allethrin to rats. Chem. Spec. Mfrs. Assoc. Proc. 

36: 59-60. fSoap and Sanit. Chem. Special Issue.] Also in 

Soap and Sanit. Chem. 26(8): 108-109. 

(174.) Stenerson, H. 

1950. Larger volume needed to bring down costs of the new allethrin 
synthetic pyrethrin products and stabilize price. .. .Prices 
for the natural product in only two years have fluctuated 
between 22 and 4-2 cents a pound. Chem. and Engin. News 
28(15): 1248. April 10. 

(175) 

1950. Smaller imports of natural pyre thrum again direct attention to 

the synthetic products now in regular commerical production. 
Chem. and Engin. News 28(41): 3544. Oct. 9. 

(176) Stoddard, R. B. 

1949. Availability of so-called "synthetic pyrethrum." U. S. Indus. 
Chem., Inc. Leaflet, 2 pp. Sept. 23. 

(177) and Dove, V. E. 

1949. Cinerin I horaolog tested. Soap and Sanit. Chem. 25(10): 118- 
121, 161. 

(178) Torpin, P. D. 

1952. A report on allethrin. McLaughlin Gormley King Company Sales 
Letter, 2 pp. May 5. 

(179) Union Carbide and Carbon Corporation 

1951. Bad news for bugs. [Advertisement.] Atlantic Monthly 187(5): 

inside back cover. May. 

(180) United States Bureau of Entomology and Plant Quarantine 

1949. Report of the £hief of the Bureau of Entomology and Plant 
Cuarantine, 1949. 63 pp. 



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1950. Report of the chief of the Bureau of Entomology and Plant 
Quarantine, 1950. 72 pp. 



- 57 - 



(182) United States Bureau of Entomology and Plant Quarantine 

1951. Report of the Chief of the Bureau of Entomology and Plant 
Quarantine, 1951. 78 pp. 

(183) United States Department of Agriculture 

1951. Quick action on research results. U. S. Dept. Agr. Clip Sheet 

CS-1U-51, 1 p. 

(184.) •— Agricultural Research Administration 

1952. USDA urges careful choice of residual insecticides in empty 

grain bins. U. S. Dept. Agr. Press Release 1003 _ 52, 1 p. 
May 7. 

(185) Agricultural Research Administration 

1949. Potent insecticide-like pyrethrum made synthetically by 
Department chemists. Press release USDA 558-49, 2 pp. 
March 18. [Processed,] 

(186) Office of Information 

1949. Government chemists rival nature in making potent insect 

killers. Press Service Picture Story No. 63, 1 p. May 1. 

(187) United States Department of the Army, Quartermaster Corps. 

1950. Military specification, insecticide, aerosol, 12-ounce dispen- 

ser MIL-I-107A5 (QMC) 6 December 50, 15 pp. 

(188) Quartermaster Corps. 

1951. Military specification, insecticide powder, pyrethrins and 

synthetics. MIL-I-11355 (QMC) 17 August 51, 19 pp. 

(189) 

1952. Military specification, insecticide, aerosol, 12-ounce dispen- 

ser MIL-I-1074.5A (QMC) 20 March 1952, 17 pp. 

(190) United States General Services Administration 

1952. Interim federal specification, Insecticides, liquid, space spray. 
0-I-55KGSA-FSS) 1 April 1952, 12 pp. 

(191) U. S. Industrial Chemicals Company 

1952. U.S.I. »s new allethrin plant scheduled for summer completion. 
Oil, Paint and Drug Rptr. 161(15): 28a-28b. April H. 
Also in Chem. and Engin. News 30: I64.9-I65O. April 21. 

(192) Viado, G. B. 

1950. The new insecticides: aldrin, dieldrin, and allethrin. Agr. 

and Indus. Life 12(9): 5, 29. 

(193) West, L. S. 

1951. The Housefly - its natural history, medical importance, and 

control. Comstock Pub. Co., Ithaca. 584. pp. 



- 58 - 



(194) Wilson, H. G., Anders, R. S., and Husman, C. N. 

1951. Field tests of several insecticides for the control of 
insecticide resistant house flies, fin press. 1 

(195) Zia-Ud-Din 

1951. Tests of lindane and other insecticides for control of Lygus 
oblineatus. Jour. Econ. Ent. 44: 773-779. 



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